Experiments show substantial performance gains.

Bug: b/135609394
Change-Id: I62a6b9dd292cafe92aa5558a84c460594b51197c
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/33772Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Tested-by: Ben Clayton <bclayton@google.com>