So i've been working on a project and wanted to render it out. I already had a very similar project rendered before all that which didn't prove difficult for my pc at all. AE estimated 20 minutes for my current project when suddenly (the video was approximately half way rendered) only one frame every 2 seconds was rendered (before it were about 3 per second). The estimated time went up until after one hour it estimated 1 h 50 min.
I cannot understand it since there are no changes in the project at the point where it slowed down. It was exactly what was rendered just a moment ago. I haven't opened any new applications during the rendering. Also i've checked my task manager and all the other things required barely any CPU or RAM. I've never had problems with extreme slow rendering before.
A couple of things may have happened. You could have run out of system resources. You could be nearing the capacity of your hard drives. To further diagnose your problem you need to take a look at your memory settings and, if you are using MP rendering, make sure that you have all CPU's accounted for. I've seen a bunch of setups where 8 cores are available but 6 or 4 are being used and even more setups where the Actual CPU's reported are 0. Then you need to make sure that your drives have plenty of space and that they have recently had a health check. If all of those things look good then you could try purging your ram every few frames. You'll find the settings by going to the AE preferences and holding down the shift key before you click General. At the bottom of the list you'll see a new section called Secret. Click there and purge every few frames.
If none of that works then we need to know everything about your composition, your render settings, your version of AE down to the last decimal point, and anything else that might have an effect on your project. It's hard to diagnose a patient if they won't put on the gown, if you know what I mean.