Laptop become slow :(

I have a 5 year old Dell Studio 2.5Ghz 4GB RAM laptop
I added a SSD hard drive and boy was it AMAZINGLY fast!

Boots up in about 10-15 seconds and is ready to use
But as of the last 6-8 weeks it's become slow and unresponsive
I don't y run much more than Chrome - with Word or Excel every now and then

It seems sluggish now
How can I diagnose??
Is there anything to test the RAM?

Important: I do something crazy! EVERY month I reinstall a clean image. Something that is virus free. This used to guarantee that I have an original state laptop EVERY month. I thought I'd mention that

Question: could it be Microsoft's latest update patches that have somehow degraded?

Also: I'm using Windows 8 - upgraded from XP - about 15 months ago

Thanks


OM