Hokking FM_Think, FM_Touch, FM_StartFrame, FM_AddToFullPack.
Or with engine : pfn_think, pfn_touch (or old one but still alive vexd_pfntouch), server_frame.
Instead of FM_Think and pfn_think, use register_think or hook Ham_Think, depending on your needs.
Instead of FM_Touch, pfn_touch and vexd_pfntouch, use register_touch or hook Ham_Touch, depending on your needs.
Try to optimize FM_AddToFullPack callback and to not hook function in lot of plugins.
Try to avoid hooking FM_StartFrame and server_frame.