Macbook Pro running slow

I have a late 08 Macbook Pro, specs are 2.53 Ghz Intel Core 2 Duo 4GB 1067 MHz DDR3. Running 10.7.4 software.

Mac has been running very slow, constantly getting the beach ball when opening applications. In safari I also constantly get the beach ball and it takes more than a minute to load some web pages. Also my fans kick on when watching videos. When I look at my Activity monitor the kernel_task is eating up a lot of CPU. Along with flash player.

I have the latest software update. Any suggestions would be great.

Thank you.

love my mac but like the doctors say - if it hurts then stop doing it.
videos - notorious for causing fan to run - watch temp and should auto shutdown
Safari - same issue for me - I stopped using safari and went to MOz and Chrome - issue gone - about to try latest safari again - latest issue to be very reliable
kernal task - stop flash recheck,
these are the first steps I would do....
good luck -

I'd recommend backing up your files and reinstalling OSX. Just to cover all bases and start fresh.

Also check available RAM/how much hard drive space you have left.

I personally would agree with the concept of starting fresh. My available hard drive space was declining and I was constantly getting beach balls. Started from scratch and got rid of lots of stuff that had accumulated which I had no need for.

I agree with the backing up and reinstalling lion idea. backup any application (not from App Store) and documents that you use on a regular basis and just transfer those to the fresh install.

Before you do that however I would reccomend iBoost up from the Mac App store. I use it on my macbook and do the quick scan which cleans up file duplicates and empties download folder if you so chose. So far I've saved about 19gb total of HDD space. Also do the disc repair. The app is free and this is much quicker and easier than reinstalling the OS.