r_displayinfo 3 – will give you basic performance information. It also gives you a big red warning when you exceed texture streaming memory!
p_profile_entities 1 – run your scene and look for fluctuations, any entity causing large peaks should be investigated.
r_stats 6 – run this to find assets with large draw calls or excessive materials, where shadows can be disabled etc.
r_stats 15 – prints detailed frame timings for specific render passes like static geometry or lighting. blue = in budget, red = over budget!
e_debugdraw 2 & 3 - 2 shows Polycount and 3 current LOD of selected entity.
e_CameraFreeze 1 - will lock your current view and allow you to look around without redrawing any elements. This allows you to see where the problems are and fix them.