Looking for a new processor

I use an inspiron 3671, my cpu is a Intel Core i5-9400, i use my desktop for blender, illustrator and after effects work and i'm currently having a lot of real time render issues

No one can make any recommendations without knowing the exact system model (Inspiron 3840, etc.), the CPU you now have (i3-3110, etc.) and exactly what you use the system for (a CPU upgrade is unlikely to help with web browsing or word processing, but would with gaming, spreadsheet work, etc.).

content rendering would benefit from a lot of ram.  Have you maxed out memory in this PC?  Max is 32 GB (2x16 GB).

i5-9400 has 6 core 6 thread.  you can consider upgrade to i7-9700 which has 8 core 8 thread.  better still is to consider a new pc that has 10-12 or more cores.

If you’ll use your Workstation just for 3D Rendering Images and Animations, or encoding Videos for that matter, you would be looking for a Computer with a CPU, that has as many cores as possible. 

The render issue may not caused by your CPU.  What graphics card do you have?  How much RAM in your system?  Upgrade CPU alone may not solved the problem.

3671 Dell video configuration either UHD630/610 or gtx1650, gt1030, gt730.