After a few cycles of suspending and waking up, on system wakeup HDD activity lasts for ~5-10 minutes (shouldn't be the RAM used instead of HDD?) and even when it is done, the whole system feels slower compared to the state after reboot.
I think it doesn't make a difference if I have any (additional) programs running while suspending.
What is causing high HDD activity after a suspend (while the RAM memory is barely filled)?
Why the system feels slower after suspending in comparison to rebooting?
This is Ubuntu 12.04 LTS x64 on a notebook 2x 1.6 GHz, 4 GB RAM (max 30% used while suspending), 4 GB swap 80% and ~70GB free HDD space for the system.