Would upgrading to SSD solve my performance issues?

My MacBook Pro specifications are:
Core2Duo 2.65 Ghz
4 GB RAM
320 GB HD

Performance is killing me literally. Really long response time.

Do you suggest to replace the Hard disk with SSD one ? Is it going to solve my MBP performance issues?

What is getting slow

I'm a software developer (code compiling, building, Xcode, IntelliJ, Sublime Text 2, tens of Chrome tabs, iTunes, Preview).

It could takes seconds to switch between running applications. A lot of spinning colored-balls.

It takes seconds to launch an application.

A RAM upgrade is inexpensive (~$70) compared to an SSD (~$1 per GB e.g. $250 for a 240GB) and based on your pagefile usage and available RAM I would start there. That being said, an SSD is a massive performance upgrade and worth every dollar in my opinion. I won't use a machine without an SSD anymore.

Links to: RAM and SSD.

Could you provide some more details as to what specifically is slow?

Note the numbers in the middle of the screenshot. Your Swap Used is higher than the amount of actual RAM you have, and there is a lot of swap activity. This indicates you are starved of RAM. I would upgrade that first. I have 8GB RAM and my swap used is 33.5MB.

An SSD would help here also, somewhat, but swapping that much on an SSD would serve to wear it out faster.

In my experience (rMBP 8GB RAM), the SSD is fast enough that swap feels almost as fast as RAM. Even at 8GB RAM, my swap is often 5–10 GBs but everything is responsive because the SSD as fast enough to keep up.

As WMD says, it will wear out the SSD though.