Hello. Installed the Blender 2.64 a couple of weeks ago and figured it would have some nice render improvments but came across the exact opposite. I do use the GPU rendering because of my ATI card but it hasn’t been this slow before. If i set the tile size to 1 to compare it to the Blender 2.63 rendering it renders much slower than it would on the 2.63 version.
Take this attached scene for example. It take about 12 minutes to render 300 samples with the 2.63 version. With the 2.64 version it takes about 10 minutes for 100 samples to render.
I believe the issue is not how to speed up Cycles render in 2.65 but that it is running slower than 2.64 and I too am having this issue with 2.65. What would take me 3 - 4 min to render in 2.64 with my GPU now takes 11 - 15 mins in 2.65. For whatever reason even though it is set to use my CUDA GPU it is using my CPU regardless.
Spongec4ke, 2.65 is faster as 2.63a with your file on my system (specs in signature).
Nevele, change your tile setting to “Resolution” of your image / 4 or something like that.
New features make a render engine also slower.
And please post your system specs, OS, GFX card and so forth.