I have a dual Xeon machine with 256GB of RAM & GTX 980, yet scrubbing the timeline in After Effects is a pain to put it mildly.
I tried using different versions of AE (CC 2015.2, CC2015.3, CC 2014, CC 12). with & without the "render multiple frames simultaneously" turned on.
And by far the fastest version I found is CC 12, however, it doesn't support 4k, and it's still slow, so I can't realistically work with it as I have a 4, 4K-monitor setup.
The rendering time is lightning fast with "render multiple frames simultaneously" turned on, which is to be expected, however, scrubbing the timeline is really hard.
I know it depends on the complexity of the project, and the codec of the footage used, however, I've worked on several different computers before with various different projects, and I've never experienced such a slow, and sluggish timeline scrubbing, mind you the specs of said computers were not even close to how powerful this machine is.
What am I missing here? What could be causing this?
CPU: 2x Intel Xeon Processor E5-2630 v3 (20M Cache, 2.40 GHz)
GPU: GeForce GTX 980 - 4 GB GDDR5
RAM: 16x DDR4 16GB 2133 MHz
Kingston 120GB SSD (OS disk)
Kingston 120GB SSD (Adobe Cache disk)
3x Kingston 120GB SSD on RAID 0 (Media Disk)
And what's your screen configuration? Simply sounds like you have issues with accelerated interface drawing.