Unfortunately security screening is a bit of a black hole. Do you know when your security screening started (ask the agent or get cbsa notes)?
It’s usually cleared in less than a year, unless csis have some serious security concerns or received some negative intel (which could include a ‘poison pen letter’ from an enemy eg an ex business partner) or you are on their watchlist. In some rare cases, individuals are suspected of being guilty by association (someone you know, or membership of a blacklisted organization). There was one doctor who had volunteered with an aid agency in Palestine, and csis had later blacklisted that agency (many years after the humanitarian work). In one case, csis received an anonymous poison pen letter against a Tamil refugee. In another case, a Tamil priest was acccused of supporting terrorism because of alleged terror financing by his employer. These issues only came to light in court; IRCC does not discuss security concerns with applicants, but such applicants are often interviewed by csis.
So if you’ve been waiting for security screening for less than a year without an interview request, keep waiting.
if however, you’ve been waiting for security clearance for 2+ years without any delay from your side (eg delay in providing documentation if asked) and If you are absolutely certain of no security suspicions (you know your situation better than anyone), then go for Mandamus. Mandamus is a legal writ that forces IRCC to finalize your application asap. It requires a lawyer. Most mandamus filings result in cases moving before any actual court case, so just filing it can be beneficial.