Without specific info about your computer, your project, your render settings and so on nobody can advise. That said, simply get used to it. AE projects can render forever depending on how complex they are and using fancy particle systems clearly qualifies as a major factor that would slow down things considerably.
For a lot of effects that rely on the GPU, you'll get a much faster render if you use the Render Cue and the default Lossless Preset for the output module. Rendering an image sequence is also usually faster than rendering to a codec. I would pick a good codec (Prorez or GoPro Cineform) or use the default Lossless preset and render a DI (digital intermediate) and then drop that file in the AME for rendering to H.264. You'll probably save time.
You might also want to consider a 3rd party rendering solution like Render Garden. It cuts my rendering time on my MacBook pro by more than 60% and on my iMac Pro by about 80% because I can assign almost all available cores to the render and still keep working in AE. Any comp that I have that takes more than a couple seconds a frame is sent to Render Garden. I have two other 3rd party renderers but RG is my favorite. It was about $100, but it saved more than that the first time I used it. It will also kick out a decent h.264 file at the same time so I don't have to go to the AME to send a proof to a client.
This is not helpful. Computers are precise and logical and trouble shooting requires data, not vague estimations. Having said that, rendering to a SSD probably will not do much to improve times.
Can you say for sure that render times are unusually long compared to your past experience?
Personally I've noticed AME being very slow at finalizing renders over the last few versions and this latest version is experiencing hangs, at least for me and one other user who's post I just responded to. At least three times this week AME has hung long enough for me to quit the render. After going into the task manager and force quitting a BG process After Effects that should not have been running I was able to restart the render and it would finish with only the slower than usual finalization. So based on your description it's entirely unclear what you are experiencing. ARe you renders finishing? If so, how long are taking exactly (not seemingly). And what are some characteristics of your project. How long is it? Are you using volumes or collisions are other very computationally intensive features?