What Mac OS for this MBP / use?

[adam9c1]

I have a 2009 MBP
2.26 C2D 4GB RAM 60GB SSD
currently running 10.11.6

I only use the machine for following:
- light web browsing usually forums or how to sites?
- streaming media via web browser (youtube or streaming sites)

This machine has been running well for this purpose months back, but now it is really laggy.
I have restarted the device today and it did help a bit at first, but again it is DOG slow.

Should I downgrade the OS to Yosemite?

 

[Lunder89]

What are the read/write speeds of the SSD, because on a SSD drive macOS shouldn't be that slow.
However downgrading to OS X Yosemite won't be enough, you need to go lower, maybe all the way down to either Mountain Lion or Lion.
At that point, there is so much software that won't run that it defeats the purpose.

 

[adam9c1]

BlackMagic
Read: 260 MB/s
Write: 70 MB/s

Crucial C300 SATAII drive
Links 3 Gigabit
Trim Support No

 

[Lunder89]

The read speed looks fine, the write speed is not much better than a regular hard drive though. However SSD should still be a large improvement.

When you say restarted, do you mean reinstalled? (as in deleted the harddrive and installed a fresh copy of macOS)

 

[Fishrrman]

How full is the hard drive?

 

[adam9c1]

Restarted the machine.

Drive has plenty of space left.
It's just the operating system and web browser.
I've installed the OS few months back and used it to browser forums or listen to streaming media only.