Speed test: two spheres, one glass, the other mirror, two planes, one checkered, one mirror (above).

2'34" in 6.3
1'31" in 6.1

Second test, same file, less reliable because I had the browser running:

2'51" in 6.3
1'39" in 6.1

Aw, come on! They must be joking! I mean, just don't release it!