Will image resizing (image_lib) exhaust my server?

[eluser]KeyStroke[/eluser]
Hi,

I'm coding a site where users can upload images to their posts. I'm trying to make it so that, when someone submits a big image, it will automatically resize it to the maximum allowed size.

I tested it locally and I got the "Allowed memory size of 8388608 bytes exhausted (tried to allocate 2319210 bytes)" error. And according to some threads here, I need to bump up my memory limit.

This seems a quite server intensive process. Does this mean that my server will be exhausted and slow down when say 1000 visitors try to upload an image at the same time for example?