you can make a script to tweak down to smoothen it out. You can use two scripts to set & undo tweaks, as since other maps are ok this may be the preferred way to do it, in order to keep it looking nice on other maps. In normal.cfg take the settings you normally use (from etmain/profiles/yourprofile/etconfig.cfg) and in tweaked change them to a fps tweak setting. Just make a new txt document with notepad or wordpad and “save as” to etmain folder, just check that it doesnt end up as normal.cfg.txt or something). For example:
nice.cfg
set cg_atmosphericEffects “1”
set r_lodbias “?” <- check your current setting
set r_picmip “0”
set r_detailtextures “1”
set r_drawSun “1”
set r_fastsky “0”
vid_restart
ugly.cfg
set cg_atmosphericEffects “0”
set r_lodbias “2”
set r_picmip “2”
set r_detailtextures “0”
set r_drawSun “0”
set r_fastsky “1”
vid_restart
Save the files to etmain and when radar loads, run /exec tweaked.cfg, and then after the map run /exec normal.cfg
With ETPro mod IIRC you can make it do this automatically (mapdefault_~.cfg iirc). Might be worth checking your preffered server’s cvar restrictions (/pb_cvarlist) before setting the tweaks, some servers like to restrict all sorts of stuff, particularily picmip and atmosphericeffects.
Anyone having fps problems fastsky is the first thing I’d turn off, on some machines it can have a significant efffect and yet largely goes unnoticed anyway (how much time do you spend staring at the sky?).