Can I speed up inkjet printing?

My HP Officejet started getting carriage jams 10 months into warranty. HP sent me a list of actions to remedy the jams, which worked - for a time. The jams became more frequent then, 3 months later, they started happening at every sheet, and when I went back to HP they said "It's out of warranty now - go to a repair agent". I pointed out it was the same in-warranty fault but they still refused to fix it.

I took the HP machine to a dump in disgust and bought a Canon instead. However, I had a lot of HP ink left which luckily fits my son's HP F2280 printer as well - so I've borrowed that to run a 500-page print job. The pages are only A5, but the 2280 is taking 35 seconds per sheet. Anybody got ideas to speed it up a bit?