Do you have reason to believe that your VPS has similar stats to your laptop? VPSes are inherently limited machines that are streamlined for common webhosting needs. They might struggle with processor- or memory-intensive tasks like image manipulation. They might also have slower filesystem writes, which can be surprisingly limiting when you're saving images.

I would ssh in and try running the raw command (e.g. with ImageMagick or whatever underlying library you're using) to see how it performs.

Some other thoughts:

• Are you generating thumbnails every time? If so you should definitely switch to caching the results. No server is going to be able to handle resizing the photos every time for every user.

• Does this include some sort of upload time? File uploads can take a while to conclude even with good transfer speeds, so consider moving the task to the background.

• There could be a bug in the library. For ImageMagick I found quite a few posts about certain OSes having processing hiccups with resizing & saving tasks:

  • "Extremely Slow ImageMagick on VPS with Ubuntu"

  • "IM: Resizing Became Very Slow After Last Upgrade"

• Also if you're just using the GD library, ImageMagick is supposedly a bit faster. (I don't have first-hand experience with GD or Intervention, so I wouldn't know)