Have you tried using another browser?
I have a few more questions, not sure if they help:
- do you have a HDD or SSD?
- After a day of working, how is the RAM usage? I'm surprised that you have no page-outs, with only 4GB of RAM.
- How long is a "very long time to boot up?" Up to one minute can be normal without SSD
- Have you tried to reset the SMC?