Sadly, the thread for results posting gives me an "Access denied. You’re not authorized to view this page." message, so, I hope that's okay if I post it here.
Previously I thought that my ancient 11-year old laptop was completely useless in terms of video editing. And it still might be so. What I recently learned and what really surprised me is that even a GeForce 310M with 512MB of DDR3 memory can significantly speed up the rendering of GPU-accelerated effects. So, looks like it is often worth enabling CUDA in Premiere Pro's project settings even with such an underpowered GPU with only 16 CUDA cores (even GTX 1050 Ti, which isn't considered to be a fast GPU by today's standards, has 768 CUDA cores).
Timeline with a single 60-second long 720p 30fps x264 video with multiple heavy GPU-accelerated effects applied to it - CUDA - 96 seconds / 18 fps
Timeline with a single 60-second long 720p 30fps x264 video with multiple heavy GPU-accelerated effects applied to it - SOFTWARE ONLY - 388 seconds / 4 fps
Timeline with a single 60-socond long 720p 30fps x264 video with a single GPU-accelerated effect applied to it - CUDA - 41 secons / 43 fps
Timeline with a single 60-second long 720p 30fps x264 video with a single GPU-accelerated effect applied to it - SOFTWARE ONLY - 99 seconds / 18 fps
imeline with a single 60-second long 720p 30fps x264 video without any effect applied to it - CUDA - 7 seconds / 238 fps
Timeline with a single 60-second long 720p 30fps x264 video without any effect applied to it - SOFTWARE ONLY - 7 seconds / 234 fps