Help upgrading Aspire E5-575
I have a 4-yr-old E5-575. I already added an extra 4GB RAM when I first bought it (for a total of 8GB) but it has been running far too slowly for me lately. I'm curious about further upgrades:
-CPU: Intel i3-7100U - I plugged it into cpu-upgrade.com and it lists several other Kaby Lake-type CPUS (mostly i5-7xxxU and i7-7xxxU) however I'm not finding any of these on newegg (I know there are other sources, that's just my go-to). Are there other options to upgrade or is that about it?
-RAM: I could go from 8GB (2x4) to 2x8 or 2x16, but how do I know if the bottleneck is the RAM or the CPU?
-GPU: Is it even possible to upgrade this? CPU-Z/CPU-ID says 'Intel HD Graphics 620'
I know that the easiest solution would be to just get a new laptop but I'd rather not stick this one in a drawer after less than 4 years. Thanks in advance