Collection authoring slow for crate files

[johnhaddon]

Description of Issue

When authoring large collections, performance is significantly poorer for .usdc files than it is for .usda.

Steps to Reproduce

Run the following script :

import time

from pxr import Usd
from pxr import UsdGeom

def runTest( fileType ) :

	title = "Testing " + fileType
	print title
	print "=" * len( title ) + "\n"

	stage = Usd.Stage.CreateNew( "/tmp/testCollections." + fileType )

	paths = []

	def makeHierarchy( prim, depth = 0 ) :

		if depth > 0 :
			paths.append( prim.GetPath() )

		if depth > 5 :
			return

		for i in range( 0, 5 ) :
			childPath = prim.GetPath().AppendChild( "p" + str( i ) )
			xform = UsdGeom.Xform.Define( stage, childPath )
			makeHierarchy( xform, depth + 1 )

	t = time.time()
	root = UsdGeom.Xform.Define( stage, "/root" )
	makeHierarchy( root )
	print "Created {} prims in {} seconds".format( len( paths ), time.time() - t )

	collection = Usd.CollectionAPI.ApplyCollection( root.GetPrim(), "allOfTheThings", Usd.Tokens.explicitOnly )

	t = time.time()
	collection.CreateIncludesRel().SetTargets( paths )
	print "Set {} targets in {} seconds".format( len( paths ), time.time() - t )

	t = time.time()
	stage.GetRootLayer().Save()
	print "Saved in {} seconds".format( time.time() - t )

runTest( "usda" )
print ""
runTest( "usdc" )

System Information (OS, Hardware)

CentOS Linux release 7.7.1908, ageing Intel workstation.

Package Versions

Tested with 20.05 and 20.08.

Build Flags

See https://github.com/GafferHQ/dependencies/blob/master/USD/config.py

[jilliene]

Filed as internal issue #USD-6385