Enter launch options at Steam > Library > Counter-Strike: Global Offensive (right-click) > Properties > Set Launch Options...
Put / write the next line in here:
-novid -high -threads 4 -freq 144 -refresh 144 -tickrate 128 -nojoy -nod3d9ex -noaafonts +exec autoexec.cfg +mat_vignette_enable 0 -processheap

Give it a try....