What? AE is not a realtime app. Do a pertinent search on the basics. And turn off MP rendering. Your system has way too little RAM for it to be of any meaningful use in relation to the number of cores plus generally initializing the extra processes for RAM previews takes longer than just previewing it with a single process.
The thing is, before this project, I had another one and after effects worked like a dream, the only thing different is that MP was turned off, and I turned it off and it is still very slow scrubbing.
Are these two projects IDENTICAL? I doubt it.
Perhaps you ought to elaborate on the differences between the two......
You have one drive to read and write with all while your Firewall and AV are governing the ONE drive? At least turn the AV & FW off for starters. Pop for a second drive, an HDD 7200rpm will write Video fast enough so your HDD I am assuming is reading and writing from the same drive you have AE installed on.