I'm sorry, I just briefly re-read your original post and missed the point that you are on a Linux box. We've done a lot of work on Linux and had very similar problems with running Domino on Linux right out of the box. A lot of the problems go away after you tune Linux for Domino.
Can I ask, what distribution of Linux are you running, what kernel version is it? Did you perform any of the tuning tips for Linux, such as increasing the file descriptors, number of processes, stack size, etc. By default Linux is NOT setup correctly out of the box to run domino effiently. YOu have to "tune" the kernel if you will. I'm hoping you won't need to re-compile glibc as that we give yout wicked fast response time and stability. A lot of the issues you are facing have been fixed by the latest distribution of Red Hat Linux and SuSE has a Domino extension pack (however you have to pay for that and you mentioned you are cash poor right now).
If you want to give it a try read the NotesBench reports we published on
http://www.notesbench.org. Look under the R5 reports (the tuning techniques apply to R6 as well). Look under platform view and find Linux or by our company name "innovative computer solutions"....
I'm short for time now but I'll try to come back with some other links for you...