From reading above it seems I should post this here. I hope that everyone who needs to read this, will.
Ok, I've read from many places that many people are getting from somewhere between 5 and 20 fps.
Now, I've done some messing around with the DoomConfig.cfg
and I've come up with some answers.
Open up your DoomConfig.cfg, scroll down and you should find this:
seta r_useStandardGL
seta r_useParhelia
seta r_useNV20
seta r_useNV30
seta r_useGL2
Now, what I did was change useStandardGL to 1, and all others to 0.
now, I have GeForce 4 MX card and when I change this setting alone, my fps jumps from around 5 to 60.
Sweet
Depending on what video card you have, you may have to use a different setting.
For a greater speed improvement, turn off the realtime generated shadow effects.
change
seta r_shadows "1"
to
seta r_shadows "0"
However, you will no longer have those badass shadows...(Though other shadows will still be there)
I still have not figured out how to speed it up when say I'm fighting against a monster for the first time (It seems to just then be loading all the graphics instead of loading it before)
Increasing the page file size seemed to help a bit, but not much.
For those that want inverted y-axis for their mouse look, change
seta m_pitch ".022"
to
seta m_pitch "-.022"
(Note I didn't figure this out myself I found in another forum, though it is a very obvious fix)
I also found this on other forums.
To change your resolution, change this value.
seta r_mode "3"
I think 3 is either 640x480 or 800x600 (the default is 3).
Increase this value to increase resolution and vice versa.
I'm still messing with the settings but I'd thought I'd post what I have figured out so far to help some folks.