diff --git a/helpers/helperslib/Buildable.py b/helpers/helperslib/Buildable.py
--- a/helpers/helperslib/Buildable.py
+++ b/helpers/helperslib/Buildable.py
@@ -204,7 +204,14 @@
 					project.dependencies.append( dependency )
 
 	# Return a list of dependencies of ourselves
-	def forProject(self, project, platform, includeSubDeps = True, checkDynamicDeps = True, currentlyKnown = []):
+	def forProject(self, project, platform, includeSubDeps = True, checkDynamicDeps = True):
+		self.dependenciesCache = {}
+		return self.forProjectRec(project, platform, includeSubDeps, checkDynamicDeps)
+
+	def forProjectRec(self, project, platform, includeSubDeps = True, checkDynamicDeps = True):
+		if not project.virtualDependency and project in self.dependenciesCache:
+			return self.dependenciesCache[project]
+
 		# Initialise - let's get ready to parse the dependencies file
 		ourDeps = finalDynamic = []
 
@@ -219,7 +226,7 @@
 
 		# Add the project level dependencies to the list of our dependencies
 		# Then run the list of our dependencies against the project negations
-		ourDeps = self._processDependencyNegation( ourDeps + project.dependencies, project.negatedDeps )
+		ourDeps = self._processDependencyNegation( project.dependencies, project.negatedDeps ) + ourDeps
 
 		# Ensure the current project is not listed (due to a dynamic dependency for instance)
 		ourDeps = [dep for dep in ourDeps if dep != project]
@@ -231,23 +238,31 @@
 			# Determine which projects we need to resolve dependencies for
 			# We process dynamic dependencies separately, as they can be recursive
 			# We also skip any dependency which has been determined as being needed by a higher up iteration to avoid unnecessary resolving of dependencies
-			toLookup = set(ourDeps) - set(finalDynamic) - set(currentlyKnown)
+			toLookup = [x for x in ourDeps if x not in finalDynamic]
 			for dependency in toLookup:
-				ourDeps = ourDeps + self.forProject(dependency, platform, includeSubDeps = True, currentlyKnown = ourDeps)
+				ourDeps = self.forProjectRec(dependency, platform, includeSubDeps = True) + ourDeps
 
 			# Process dynamic dependencies here
 			# We won't look at other dynamic dependency rules when we do this
 			# This is slightly limiting, but it is otherwise possible to end up in a dependency resolution loop
-			dynamicLookup = set(ourDeps) & set(finalDynamic)
+			dynamicLookup = ourDeps + finalDynamic
 			for dependency in dynamicLookup:
-				ourDeps = ourDeps + self.forProject(dependency, platform, includeSubDeps = True, checkDynamicDeps = False, currentlyKnown = ourDeps)
+				ourDeps = self.forProjectRec(dependency, platform, includeSubDeps = True, checkDynamicDeps = False) + ourDeps
 
 		# Re-ensure the current project is not listed and that they are not virtual
 		# Dynamic dependency resolution of sub-dependencies may have re-added it
 		ourDeps = [dep for dep in ourDeps if dep != project and not dep.virtualDependency]
 
 		# Ensure we don't have any duplicates
-		return list(set(ourDeps))
+		deps = self.unique(ourDeps)
+
+		self.dependenciesCache[project] = deps
+
+		return deps
+
+	def unique(self, sequence):
+		seen = set()
+		return [x for x in sequence if not (x in seen or seen.add(x))]
 
 	def _resolveDynamicDependencies(self, project, dynamicDeps):
 		# Go over the dynamic dependencies list we have and see if we match
@@ -264,7 +279,7 @@
 
 	def _processDependencyNegation(self, dependentProjects, negatedProjects):
 		# Remove any dependencies which have been negated
-		return list( set(dependentProjects) - set(negatedProjects) )
+		return [x for x in dependentProjects if not x in negatedProjects]
 
 # Class which can parse the product-definitions.yaml file
 # This allows us to determine what build combinations we need to support