after i upgraded from Blender 2.79 to 2.79b yesterday in order to use the cpu+gpu feature which btw apparently no longer exists . I tried to notice if there was any difference on the render time of a scene with emission particles flow + blur that i rendered just before, after the upgrade i opened the same untouched file with same Blender parameters (even user preferences), and this is the weirdest part... every time i hit F12 i got a longer render time and it seems like the light trail of the particles is getting longer like if the animation is running. (it's not, it has always been frame 107). I filled all of the 8 render result slots consecutively with the same frame and i got 8 results (12sec/13/15/20/30/54/1min44/3min) (the more blured it gets or the longer the particle's light trails are, the longer the time it takes to render) and it seems like the time is going up to the infinity as long as i keep rendering the same image, it takes longer and the result is more "changed"... Any idea about the reason it is changing ? thank you and sorry for my bad english.
PC specs: - CPU I5-3340 - GPU GTX 560ti - RAM DDR3 1333MHZ 16Gb - Motherboard MSI Z77A-G43 - OS Windows 7 ultimate
Ps: i got the Blur option turned on ofcourse and the shutter set to 1. no caustics and all light bounces set to 0 and samples set to 100 .