Thanks to Karl Jones, Handy Vandals Almanac. http://www.karljones.com/halflife/almanac.asp
R_speed is a measure of how many polygons the game engine render at any given time. Polygons are triangles, the simplest possible shape. The engine draws the triangles to the screen.
There are two types of polygons:
wpolys (world polygons) Wpolys: all brushes (including brush-based entities like doors) increase wpolys. This value is typically used to describe r_speeds. When you compile a map, the compiler generates a list of wpoly triangles based upon the brushes in the map.
epolys (entity polygons) Epolys are the polygons in any model-based entity like players, monsters, items, weapons.
End Handy Vandal Info.....
Start of stuff I know.....
So what are you looking at?
If you type r_speeds 1 at the console in your map you will be shown a scrolling list of numbers like this;
48fps 10ms 560wpoly 1870epoly }
48fps 10ms 560wpoly 1870epoly } These numbers may be constantly changing
48fps 10ms 560wpoly 1870epoly }
The figure you are interested in is the wpoly figure (560 in this case). This is what most people are talking about when they say that a map had high r_speeds and lags the play.
Redraw or Refresh speed. Commonly used for the wpoly count. r_speeds affect lag and FPS.
If you want to have a look at the r_speeds of the map you're constructing, enter "r_speeds 1" at the console. Then run around, and you will get a better Idea of how r_speeds effect your map, and possible Laggy areas.
What you are looking for, as a general rule is a Wpoly of around 400 to 600 or less ( recently forum comments have indicated wpoly counts of around 800 are acceptable). I have read differet ideas on this, but the consensus is that these figures produce a playable multiplayer map without too much Lag. Don't get too frustrated by this, most people go mad trying to keep R_speeds down and forget actual fun while playing. High traffic areas should be kept within these limits, if you can manage it, but I have found the best way of testing a map is to run it on an old machine. PII 400 or less with a really average graphics card. This will show up the problem areas straight away. Large outside areas really push the r_speeds up, fine in single player but a hassle in multiplayer, This doesn't mean that you shouldn't use them, it just means that you really should try to limit large box type areas. If you don't want to use r_speeds 1 at the console then try another Tip I read on Happy Vandals Almanac that said to get an RPG, fire all the rounds and run round with the trigger pressed. it should make a clicky sound. If this isn't constant, then there is a possibility that where you are in the map is just too busy.
Read the section in the help file on reducing polygon counts, and try removing things one at a time, until the map is smooth again. Make use of entity brushes for lights and fixtures as they don't split the world brushes up.
Another thing to try is "Visable Blocking", by this they mean placing solid brushes to block line of sight between big rooms. Entity brushes do not block Vis as far as the engine is concerned.
Another option is including the zhlt.wad file in your textures and making use of HINT brushes. Too deep for the Glossary, but hopefully I will have finished a tutorial on r_speeds soon.
At the end of the day, don't get too obsesed with R_speeds if your producing a map for yourself and your mates, afterall mapping is all about discovery and fun.
This is probably the best description of what r_speeds are all about.