Here are the settings I use. Do a search for fozzer's post on ss settings. There are serveral things you can do to adjust the frequency, size, etc. Best way to know what works on your server is to tweak them. You could start off with my settings (which are not tweaked much from the default) or your could make other adjustments. Either way....since you play on the server.....you will learn what ss setting changes affect your system....as far as lag and such.
pb_sv_SsFloor 1 //[Low screenshot filename serial #]
pb_sv_SsCeiling 999999 //[High screenshot filename serial #]
pb_sv_SsCmd "" //[Filename of system command to run after screenshots]
pb_sv_SsWidth 640 //[Requested pixel width of remote screenshots]
pb_sv_SsHeight 480 //[Requested pixel height of remote screenshots]
pb_sv_SsXpct 50 //[Percentage across screen for remote screenshots]
pb_sv_SsYpct 50 //[Percentage down screen for remote screenshots]
pb_sv_SsSrate 2 //[sample Rate for remote screenshots]
pb_sv_SsDelay 0 //[Maximum delay client waits before capturing screenshot]
pb_sv_SsPath "" //[Path where remote screenshots are saved]
pb_sv_AutoSsFrom 60 //[Min # of seconds to wait before requesting next ss]
pb_sv_AutoSsTo 1200 //[Max # of seconds to wait before requesting next ss]
pb_sv_AutoSs 1 //[0=No, 1=Yes (default=0)]
pb_sv_ssLogging 0 //[1=Reg. Log, 2=SS Log, 3=Both, 0=Neither]
pb_sv_ssTimeout 0 //[seconds]