Why is scrolling jumpy on web pages? e.g images are like mini speed bumps.

I'm hoping you can help me understand why on what should be a fairly well geared machine I'm getting chunky scrolling on web pages. e.g I don't get a nice fluid scroll, but like it struggles at bits... smooth for a bit and then jumps.

I'm using a logitech darkfield mouse that has smooth scrolling and in simple things like a text file it scrolls as expected. So I don't believe its the mouse.

So what is the hold up? Is my graphics card (radeon 5770) unable to keep up with the frames per second required to scroll down through a page or something like this?

It seems to me if I look closely, its when a new picture scrolls onto the page, it hits it like a speed bump. Note: this is when the page is fully loaded.

I'm on a 2 x quad-core 2.4ghz 2010 model. One would imagine I could scroll through a 500kb page like cutting through already melted butter with a fine carbon blade, but no, I feel like its not that way at all. What am I missing?

 

You're right - safari is definitely smoother.

But I just noticed I also get the same jagged scrolling just through my Applications folder.

Could it have something to do with hdd speed?