Michael Abrash (author of the Black Book) is currently doing VR on GPUs. He's been talking recently about how the GPUs need at least 10x more power, so in some sense he's not impressed by hardware accelerated graphics either. But I'll bet a dollar right now that he won't settle for a Celeron. ;) It doesn't sound like you're doing much that's 3d or graphically demanding? Not surprising you don't need a GPU.

My laptop has a GPU, and also has separate dedicated video decode hardware, so doesn't need either GPU or CPU for most video -- far easier on the battery and doesn't hog the CPU.

Aside from games, you might be interested in a GPU for CNNs or mining virtual currencies. There's no question about the effectiveness over laptop CPUs.

Have you seen WebRender? It sports impressive performance, which does help on real-world applications/sites, especially on low-end HW. While its performance gains probably come from multiple sources, pushing work to GPU is afaik one of the main ones.

https://github.com/servo/webrender/wiki

Also, I'm reminded of Anandtech review of the 1st-gen rMBP:

At 2880 x 1800 most interactions are smooth but things like zooming windows or scrolling on certain web pages is clearly sub-30fps. At the higher scaled resolutions, since the GPU has to render as much as 9.2MP, even UI performance can be sluggish [...] But there are other limitations: many elements of screen drawing are still done on the CPU, and as largely serial architectures their ability to scale performance with dramatically higher resolutions is limited.

Some elements of drawing in Safari for example aren’t handled by the GPU. Quickly scrolling up and down on the AnandTech home page will peg one of the four IVB cores in the rMBP at 100%

The GPU has an easy time with its part of the process but the CPU’s workload is borderline too much for a single core to handle. Throw a more complex website at it and things get bad quickly. Facebook combines a lot of compressed images with text - every single image is decompressed on the CPU before being handed off to the GPU. Combine that with other elements that are processed on the CPU and you get a recipe for choppy scrolling.

To quantify exactly what I was seeing I measured frame rate while scrolling as quickly as possible through my Facebook news feed in Safari on the rMBP as well as my 2011 15-inch High Res MacBook Pro. While last year’s MBP delivered anywhere from 46 - 60 fps during this test, the rMBP hovered around 20 fps (18 - 24 fps was the typical range).

The good news is Mountain Lion provides some relief. At WWDC Apple mentioned the next version of Safari is ridiculously fast, but it wasn’t specific about why. It turns out that Safari leverages Core Animation in Mountain Lion and more GPU accelerated as a result. Facebook is still a challenge because of the mixture of CPU decoded images and a standard web page, but the experience is a bit better. Repeating the same test as above I measured anywhere from 20 - 30 fps while scrolling through Facebook on ML’s Safari

http://www.anandtech.com/show/6023/the-nextgen-macbook-pro-w...

I think that demonstrates clearly how GPUs are essential for todays rich UIs, especially when targeting higher resolutions. Yes, the examples here are for web, but I don't see any reason why the situation wouldn't be the same for any other stack.

If your web site is unusable without a GPU you have done something wrong.