diff --git a/OpenRA.Game/Traits/Health.cs b/OpenRA.Game/Traits/Health.cs
index 9955ec78ed..6566068d21 100755
--- a/OpenRA.Game/Traits/Health.cs
+++ b/OpenRA.Game/Traits/Health.cs
@@ -100,16 +100,21 @@ namespace OpenRA.Traits
 
 		public void InflictDamage(Actor self, Actor attacker, int damage, DamageWarhead warhead, bool ignoreModifiers)
 		{
-			if (IsDead) return;		/* overkill! don't count extra hits as more kills! */
+			// Overkill! don't count extra hits as more kills!
+			if (IsDead)
+				return;
 
 			var oldState = this.DamageState;
-			/* apply the damage modifiers, if we have any. */
-			var modifier = self.TraitsImplementing<IDamageModifier>()
-				.Concat(self.Owner.PlayerActor.TraitsImplementing<IDamageModifier>())
-				.Select(t => t.GetDamageModifier(attacker, warhead)).Product();
 
-			if (!ignoreModifiers)
-				damage = damage > 0 ? (int)(damage * modifier) : damage;
+			// Apply any damage modifiers
+			if (!ignoreModifiers && damage > 0)
+			{
+				var modifiers = self.TraitsImplementing<IDamageModifier>()
+					.Concat(self.Owner.PlayerActor.TraitsImplementing<IDamageModifier>())
+					.Select(t => t.GetDamageModifier(attacker, warhead));
+
+				damage = Util.ApplyPercentageModifiers(damage, modifiers);
+			}
 
 			hp = Exts.Clamp(hp - damage, 0, MaxHP);
 
diff --git a/OpenRA.Game/Traits/TraitsInterfaces.cs b/OpenRA.Game/Traits/TraitsInterfaces.cs
index 3ea4d94368..be008b25ba 100644
--- a/OpenRA.Game/Traits/TraitsInterfaces.cs
+++ b/OpenRA.Game/Traits/TraitsInterfaces.cs
@@ -167,9 +167,9 @@ namespace OpenRA.Traits
 	}
 
 	public interface IRenderModifier { IEnumerable<IRenderable> ModifyRender(Actor self, WorldRenderer wr, IEnumerable<IRenderable> r); }
-	public interface IDamageModifier { float GetDamageModifier(Actor attacker, DamageWarhead warhead); }
-	public interface ISpeedModifier { decimal GetSpeedModifier(); }
-	public interface IFirepowerModifier { float GetFirepowerModifier(); }
+	public interface IDamageModifier { int GetDamageModifier(Actor attacker, DamageWarhead warhead); }
+	public interface ISpeedModifier { int GetSpeedModifier(); }
+	public interface IFirepowerModifier { int GetFirepowerModifier(); }
 	public interface ILoadsPalettes { void LoadPalettes(WorldRenderer wr); }
 	public interface IPaletteModifier { void AdjustPalette(IReadOnlyDictionary<string, MutablePalette> b); }
 	public interface IPips { IEnumerable<PipType> GetPips(Actor self); }
diff --git a/OpenRA.Game/Traits/Util.cs b/OpenRA.Game/Traits/Util.cs
index 6268bcf1d5..0a6a999f82 100644
--- a/OpenRA.Game/Traits/Util.cs
+++ b/OpenRA.Game/Traits/Util.cs
@@ -138,5 +138,15 @@ namespace OpenRA.Traits
 			var cells = target.Positions.Select(p => w.Map.CellContaining(p)).Distinct();
 			return ExpandFootprint(cells, true);
 		}
+
+		public static int ApplyPercentageModifiers(int number, IEnumerable<int> percentages)
+		{
+			// See the comments of PR#6079 for a faster algorithm if this becomes a performance bottleneck
+			var a = (decimal)number;
+			foreach (var p in percentages)
+				a *= p / 100m;
+
+			return (int)a;
+		}
 	}
 }
diff --git a/OpenRA.Mods.D2k/ThrowsShrapnel.cs b/OpenRA.Mods.D2k/ThrowsShrapnel.cs
index 6a219bd97b..32e963acad 100644
--- a/OpenRA.Mods.D2k/ThrowsShrapnel.cs
+++ b/OpenRA.Mods.D2k/ThrowsShrapnel.cs
@@ -48,8 +48,10 @@ namespace OpenRA.Mods.D2k
 					{
 						Weapon = wep,
 						Facing = self.World.SharedRandom.Next(-1, 255),
+
+						// TODO: Convert to ints
 						FirepowerModifier = self.TraitsImplementing<IFirepowerModifier>()
-							.Select(a => a.GetFirepowerModifier())
+							.Select(a => a.GetFirepowerModifier() / 100f)
 							.Product(),
 
 						Source = self.CenterPosition,
diff --git a/OpenRA.Mods.RA/Activities/Demolish.cs b/OpenRA.Mods.RA/Activities/Demolish.cs
index 97f9a97924..045eccbea0 100644
--- a/OpenRA.Mods.RA/Activities/Demolish.cs
+++ b/OpenRA.Mods.RA/Activities/Demolish.cs
@@ -50,16 +50,17 @@ namespace OpenRA.Mods.RA.Activities
 					if (target.Type != TargetType.Actor)
 						return;
 
-					// Invulnerable actors can't be demolished
-					var modifier = (float)target.Actor.TraitsImplementing<IDamageModifier>()
-						.Concat(self.Owner.PlayerActor.TraitsImplementing<IDamageModifier>())
-						.Select(t => t.GetDamageModifier(self, null)).Product();
+
 
 					var demolishable = target.Actor.TraitOrDefault<IDemolishable>();
 					if (demolishable == null || !demolishable.IsValidTarget(target.Actor, self))
 						return;
 
-					if (modifier > 0)
+					var modifiers = target.Actor.TraitsImplementing<IDamageModifier>()
+						.Concat(self.Owner.PlayerActor.TraitsImplementing<IDamageModifier>())
+						.Select(t => t.GetDamageModifier(self, null));
+
+					if (Util.ApplyPercentageModifiers(100, modifiers) > 0)
 						demolishable.Demolish(target.Actor, self);
 				}));
 			});
diff --git a/OpenRA.Mods.RA/Air/Aircraft.cs b/OpenRA.Mods.RA/Air/Aircraft.cs
index 55964bdfee..61fef40569 100644
--- a/OpenRA.Mods.RA/Air/Aircraft.cs
+++ b/OpenRA.Mods.RA/Air/Aircraft.cs
@@ -203,10 +203,9 @@ namespace OpenRA.Mods.RA.Air
 		{
 			get
 			{
-				decimal ret = info.Speed;
-				foreach (var t in self.TraitsImplementing<ISpeedModifier>())
-					ret *= t.GetSpeedModifier();
-				return (int)ret;
+				var modifiers = self.TraitsImplementing<ISpeedModifier>()
+					.Select(m => m.GetSpeedModifier());
+				return Util.ApplyPercentageModifiers(info.Speed, modifiers);
 			}
 		}
 
diff --git a/OpenRA.Mods.RA/Armament.cs b/OpenRA.Mods.RA/Armament.cs
index aee2b84e2f..176488022e 100644
--- a/OpenRA.Mods.RA/Armament.cs
+++ b/OpenRA.Mods.RA/Armament.cs
@@ -153,8 +153,10 @@ namespace OpenRA.Mods.RA
 			{
 				Weapon = Weapon,
 				Facing = legacyFacing,
+
+				// TODO: Convert to ints
 				FirepowerModifier = self.TraitsImplementing<IFirepowerModifier>()
-					.Select(a => a.GetFirepowerModifier())
+					.Select(a => a.GetFirepowerModifier() / 100f)
 					.Product(),
 
 				Source = muzzlePosition,
diff --git a/OpenRA.Mods.RA/Attack/AttackPopupTurreted.cs b/OpenRA.Mods.RA/Attack/AttackPopupTurreted.cs
index a4a66b8a92..85a36478fc 100644
--- a/OpenRA.Mods.RA/Attack/AttackPopupTurreted.cs
+++ b/OpenRA.Mods.RA/Attack/AttackPopupTurreted.cs
@@ -23,8 +23,8 @@ namespace OpenRA.Mods.RA
 		public int CloseDelay = 125;
 		public int DefaultFacing = 0;
 
-		[Desc("The factor damage received is multiplied by while this actor is closed.")]
-		public float ClosedDamageMultiplier = 0.5f;
+		[Desc("The percentage of damage that is received while this actor is closed.")]
+		public int ClosedDamageMultiplier = 50;
 
 		public override object Create(ActorInitializer init) { return new AttackPopupTurreted(init, this); }
 	}
@@ -105,9 +105,9 @@ namespace OpenRA.Mods.RA
 			}
 		}
 
-		public float GetDamageModifier(Actor attacker, DamageWarhead warhead)
+		public int GetDamageModifier(Actor attacker, DamageWarhead warhead)
 		{
-			return state == PopupState.Closed ? info.ClosedDamageMultiplier : 1f;
+			return state == PopupState.Closed ? info.ClosedDamageMultiplier : 100;
 		}
 	}
 }
diff --git a/OpenRA.Mods.RA/GainsStatUpgrades.cs b/OpenRA.Mods.RA/GainsStatUpgrades.cs
index f7889e1446..2e1527ed70 100644
--- a/OpenRA.Mods.RA/GainsStatUpgrades.cs
+++ b/OpenRA.Mods.RA/GainsStatUpgrades.cs
@@ -19,13 +19,13 @@ namespace OpenRA.Mods.RA
 	public class GainsStatUpgradesInfo : ITraitInfo
 	{
 		public readonly string FirepowerUpgrade = "firepower";
-		public readonly float[] FirepowerModifier = { 1.1f, 1.15f, 1.2f, 1.5f };
+		public readonly int[] FirepowerModifier = { 110, 115, 120, 150 };
 
 		public readonly string ArmorUpgrade = "armor";
-		public readonly float[] ArmorModifier = { 1.1f, 1.2f, 1.3f, 1.5f };
+		public readonly int[] ArmorModifier = { 110, 120, 130, 150 };
 
 		public readonly string SpeedUpgrade = "speed";
-		public readonly decimal[] SpeedModifier = { 1.1m, 1.15m, 1.2m, 1.5m };
+		public readonly int[] SpeedModifier = { 110, 115, 120, 150 };
 
 		public object Create(ActorInitializer init) { return new GainsStatUpgrades(this); }
 	}
@@ -60,19 +60,19 @@ namespace OpenRA.Mods.RA
 				speedLevel = (speedLevel + mod).Clamp(0, info.SpeedModifier.Length);
 		}
 
-		public float GetDamageModifier(Actor attacker, DamageWarhead warhead)
+		public int GetDamageModifier(Actor attacker, DamageWarhead warhead)
 		{
-			return armorLevel > 0 ? 1 / info.ArmorModifier[armorLevel - 1] : 1;
+			return armorLevel > 0 ? 1 / info.ArmorModifier[armorLevel - 1] : 100;
 		}
 
-		public float GetFirepowerModifier()
+		public int GetFirepowerModifier()
 		{
-			return firepowerLevel > 0 ? info.FirepowerModifier[firepowerLevel - 1] : 1;
+			return firepowerLevel > 0 ? info.FirepowerModifier[firepowerLevel - 1] : 100;
 		}
 
-		public decimal GetSpeedModifier()
+		public int GetSpeedModifier()
 		{
-			return speedLevel > 0 ? info.SpeedModifier[speedLevel - 1] : 1m;
+			return speedLevel > 0 ? info.SpeedModifier[speedLevel - 1] : 100;
 		}
 	}
 }
diff --git a/OpenRA.Mods.RA/Harvester.cs b/OpenRA.Mods.RA/Harvester.cs
index a18a53e208..1a06bd35e3 100644
--- a/OpenRA.Mods.RA/Harvester.cs
+++ b/OpenRA.Mods.RA/Harvester.cs
@@ -31,8 +31,8 @@ namespace OpenRA.Mods.RA
 		public readonly int HarvestFacings = 0;
 		[Desc("Which resources it can harvest.")]
 		public readonly string[] Resources = { };
-		[Desc("How much it is slowed down when returning to the refinery.")]
-		public readonly decimal FullyLoadedSpeed = .85m;
+		[Desc("Percentage of maximum speed when fully loaded.")]
+		public readonly int FullyLoadedSpeed = 85;
 		[Desc("Initial search radius (in cells) from the refinery that created us.")]
 		public readonly int SearchFromProcRadius = 24;
 		[Desc("Search radius (in cells) from the last harvest order location to find more resources.")]
@@ -418,9 +418,9 @@ namespace OpenRA.Mods.RA
 
 		public bool ShouldExplode(Actor self) { return !IsEmpty; }
 
-		public decimal GetSpeedModifier()
+		public int GetSpeedModifier()
 		{
-			return 1m - (1m - Info.FullyLoadedSpeed) * contents.Values.Sum() / Info.Capacity;
+			return 100 - (100 - Info.FullyLoadedSpeed) * contents.Values.Sum() / Info.Capacity;
 		}
 
 		class HarvestOrderTargeter : IOrderTargeter
diff --git a/OpenRA.Mods.RA/Invulnerable.cs b/OpenRA.Mods.RA/Invulnerable.cs
index b05950fed7..b4407d3377 100644
--- a/OpenRA.Mods.RA/Invulnerable.cs
+++ b/OpenRA.Mods.RA/Invulnerable.cs
@@ -18,6 +18,6 @@ namespace OpenRA.Mods.RA
 
 	class Invulnerable : IDamageModifier
 	{
-		public float GetDamageModifier(Actor attacker, DamageWarhead warhead) { return 0.0f; }
+		public int GetDamageModifier(Actor attacker, DamageWarhead warhead) { return 0; }
 	}
 }
diff --git a/OpenRA.Mods.RA/IronCurtainable.cs b/OpenRA.Mods.RA/IronCurtainable.cs
index 0c8db3f3ab..dfe50c7dc2 100644
--- a/OpenRA.Mods.RA/IronCurtainable.cs
+++ b/OpenRA.Mods.RA/IronCurtainable.cs
@@ -28,9 +28,9 @@ namespace OpenRA.Mods.RA
 				RemainingTicks--;
 		}
 
-		public float GetDamageModifier(Actor attacker, DamageWarhead warhead)
+		public int GetDamageModifier(Actor attacker, DamageWarhead warhead)
 		{
-			return (RemainingTicks > 0) ? 0.0f : 1.0f;
+			return RemainingTicks > 0 ? 0 : 100;
 		}
 
 		public void Activate(Actor self, int duration)
diff --git a/OpenRA.Mods.RA/Move/Mobile.cs b/OpenRA.Mods.RA/Move/Mobile.cs
index b83ea123cc..0a8b94f030 100755
--- a/OpenRA.Mods.RA/Move/Mobile.cs
+++ b/OpenRA.Mods.RA/Move/Mobile.cs
@@ -487,13 +487,15 @@ namespace OpenRA.Mods.RA.Move
 			if (index == -1)
 				return 0;
 
+			// TODO: Convert to integers
 			var speed = Info.TilesetTerrainInfo[self.World.TileSet][index].Speed;
 			if (speed == decimal.Zero)
 				return 0;
 
 			speed *= Info.Speed;
 			foreach (var t in self.TraitsImplementing<ISpeedModifier>())
-				speed *= t.GetSpeedModifier();
+				speed *= t.GetSpeedModifier() / 100m;
+
 			return (int)(speed / 100);
 		}
 
diff --git a/OpenRA.Mods.RA/ScaredyCat.cs b/OpenRA.Mods.RA/ScaredyCat.cs
index 01904e1de2..0e5a526818 100644
--- a/OpenRA.Mods.RA/ScaredyCat.cs
+++ b/OpenRA.Mods.RA/ScaredyCat.cs
@@ -17,7 +17,7 @@ namespace OpenRA.Mods.RA
 	class ScaredyCatInfo : ITraitInfo
 	{
 		public readonly int PanicLength = 25 * 10;
-		public readonly decimal PanicSpeedModifier = 2;
+		public readonly int PanicSpeedModifier = 200;
 		public readonly int AttackPanicChance = 20;
 
 		public object Create(ActorInitializer init) { return new ScaredyCat(init.self, this); }
@@ -74,9 +74,9 @@ namespace OpenRA.Mods.RA
 				Panic();
 		}
 
-		public decimal GetSpeedModifier()
+		public int GetSpeedModifier()
 		{
-			return Panicking ? Info.PanicSpeedModifier : 1;
+			return Panicking ? Info.PanicSpeedModifier : 100;
 		}
 	}
 }
diff --git a/OpenRA.Mods.RA/Scripting/ScriptInvulnerable.cs b/OpenRA.Mods.RA/Scripting/ScriptInvulnerable.cs
index eebcf35013..f2c8e5f067 100644
--- a/OpenRA.Mods.RA/Scripting/ScriptInvulnerable.cs
+++ b/OpenRA.Mods.RA/Scripting/ScriptInvulnerable.cs
@@ -20,9 +20,9 @@ namespace OpenRA.Mods.RA
 	{
 		public bool Invulnerable = false;
 
-		public float GetDamageModifier(Actor attacker, DamageWarhead warhead)
+		public int GetDamageModifier(Actor attacker, DamageWarhead warhead)
 		{
-			return Invulnerable ? 0.0f : 1.0f;
+			return Invulnerable ? 0 : 100;
 		}
 	}
 }
diff --git a/OpenRA.Mods.RA/TakeCover.cs b/OpenRA.Mods.RA/TakeCover.cs
index 6d64de1782..3334ef30b6 100644
--- a/OpenRA.Mods.RA/TakeCover.cs
+++ b/OpenRA.Mods.RA/TakeCover.cs
@@ -21,8 +21,8 @@ namespace OpenRA.Mods.RA
 			"Measured in game ticks. Default is 4 seconds.")]
 		public readonly int ProneTime = 100;
 
-		[Desc("How quickly we should go from standing to prone.")]
-		public readonly decimal ProneSpeed = .5m;
+		[Desc("Prone movement speed as a percentage of the normal speed.")]
+		public readonly int SpeedModifier = 50;
 
 		public readonly WVec ProneOffset = new WVec(85, 0, -171);
 
@@ -61,14 +61,14 @@ namespace OpenRA.Mods.RA
 				LocalOffset = WVec.Zero;
 		}
 
-		public float GetDamageModifier(Actor attacker, DamageWarhead warhead)
+		public int GetDamageModifier(Actor attacker, DamageWarhead warhead)
 		{
-			return IsProne && warhead != null ? warhead.ProneModifier / 100f : 1f;
+			return IsProne && warhead != null ? warhead.ProneModifier : 100;
 		}
 
-		public decimal GetSpeedModifier()
+		public int GetSpeedModifier()
 		{
-			return IsProne ? Info.ProneSpeed : 1m;
+			return IsProne ? Info.SpeedModifier : 100;
 		}
 	}
 
diff --git a/OpenRA.Utility/UpgradeRules.cs b/OpenRA.Utility/UpgradeRules.cs
index bb6ef61b7c..cffba0a7ca 100644
--- a/OpenRA.Utility/UpgradeRules.cs
+++ b/OpenRA.Utility/UpgradeRules.cs
@@ -26,6 +26,12 @@ namespace OpenRA.Utility
 			input = "{0}c{1}".F(cells, subcells);
 		}
 
+		static void ConvertFloatArrayToPercentArray(ref string input)
+		{
+			input = string.Join(", ", input.Split(',')
+				.Select(s => ((int)(float.Parse(s) * 100)).ToString()));
+		}
+
 		static void ConvertPxToRange(ref string input)
 		{
 			ConvertPxToRange(ref input, 1, 1);
@@ -402,6 +408,34 @@ namespace OpenRA.Utility
 					}
 				}
 
+				// Modifiers were changed to integer percentages
+				if (engineVersion < 20140812)
+				{
+					if (depth == 2 && node.Key == "ClosedDamageMultiplier" && parentKey == "AttackPopupTurreted")
+						ConvertFloatArrayToPercentArray(ref node.Value.Value);
+
+					if (depth == 2 && node.Key == "ArmorModifier" && parentKey == "GainsStatUpgrades")
+						ConvertFloatArrayToPercentArray(ref node.Value.Value);
+
+					if (depth == 2 && node.Key == "FullyLoadedSpeed" && parentKey == "Harvester")
+						ConvertFloatArrayToPercentArray(ref node.Value.Value);
+
+					if (depth == 2 && node.Key == "PanicSpeedModifier" && parentKey == "ScaredyCat")
+						ConvertFloatArrayToPercentArray(ref node.Value.Value);
+
+					if (depth == 2 && node.Key == "ProneSpeed" && parentKey == "TakeCover")
+					{
+						node.Key = "SpeedModifier";
+						ConvertFloatArrayToPercentArray(ref node.Value.Value);
+					}
+
+					if (depth == 2 && node.Key == "SpeedModifier" && parentKey == "GainsStatUpgrades")
+						ConvertFloatArrayToPercentArray(ref node.Value.Value);
+
+					if (depth == 2 && node.Key == "FirepowerModifier" && parentKey == "GainsStatUpgrades")
+						ConvertFloatArrayToPercentArray(ref node.Value.Value);
+				}
+
 				UpgradeActorRules(engineVersion, ref node.Value.Nodes, node, depth + 1);
 			}
 		}
diff --git a/mods/cnc/rules/defaults.yaml b/mods/cnc/rules/defaults.yaml
index 036ffe7060..8081af4080 100644
--- a/mods/cnc/rules/defaults.yaml
+++ b/mods/cnc/rules/defaults.yaml
@@ -151,7 +151,7 @@
 	TargetableUnit:
 		TargetTypes: Ground, Infantry
 	TakeCover:
-		ProneSpeed: 0.6
+		SpeedModifier: 60
 	RenderInfantryProne:
 	AttackMove:
 	Passenger:
diff --git a/mods/ts/rules/defaults.yaml b/mods/ts/rules/defaults.yaml
index e867dca41a..223141f59e 100644
--- a/mods/ts/rules/defaults.yaml
+++ b/mods/ts/rules/defaults.yaml
@@ -117,9 +117,9 @@
 			500: firepower, armor, speed
 			1000: firepower, armor, speed
 	GainsStatUpgrades:
-		FirepowerModifier: 1.2, 1.5
-		ArmorModifier: 1.2, 1.5
-		SpeedModifier: 1.2, 1.5
+		FirepowerModifier: 120, 150
+		ArmorModifier: 120, 150
+		SpeedModifier: 120, 150
 	GivesExperience:
 	DrawLineToTarget:
 	ActorLostNotification:
@@ -206,9 +206,9 @@
 			500: firepower, armor, speed
 			1000: firepower, armor, speed
 	GainsStatUpgrades:
-		FirepowerModifier: 1.2, 1.5
-		ArmorModifier: 1.2, 1.5
-		SpeedModifier: 1.2, 1.5
+		FirepowerModifier: 120, 150
+		ArmorModifier: 120, 150
+		SpeedModifier: 120, 150
 	GivesExperience:
 	DrawLineToTarget:
 	ActorLostNotification:
@@ -258,9 +258,9 @@
 			500: firepower, armor, speed
 			1000: firepower, armor, speed
 	GainsStatUpgrades:
-		FirepowerModifier: 1.2, 1.5
-		ArmorModifier: 1.2, 1.5
-		SpeedModifier: 1.2, 1.5
+		FirepowerModifier: 120, 150
+		ArmorModifier: 120, 150
+		SpeedModifier: 120, 150
 	GivesExperience:
 	DrawLineToTarget:
 	ActorLostNotification:
@@ -304,9 +304,9 @@
 			500: firepower, armor, speed
 			1000: firepower, armor, speed
 	GainsStatUpgrades:
-		FirepowerModifier: 1.2, 1.5
-		ArmorModifier: 1.2, 1.5
-		SpeedModifier: 1.2, 1.5
+		FirepowerModifier: 120, 150
+		ArmorModifier: 120, 150
+		SpeedModifier: 120, 150
 	GivesExperience:
 	DrawLineToTarget:
 	ActorLostNotification: