Valorant FPS drops have been a problem for some. A Valorant developer responded to a Reddit post about extreme FPS drops when players fire their weapons or use their abilities. Which you'll notice are major components of the game, and represent the worst times to have dramatic FPS drops.
In the past few weeks, players have come across more and more issues in the Closed Beta, and the increase of cheaters. It's to be expected during betas, but the massive increase in cheaters after Riot Games praised their Anti-Cheat software is a bit disheartening.
Valorant FPS Drops: Dev Responds to Reddit Post About Extreme FPS Drops During Gun Fights
Riot Games dev Koalifier explains they're aware that FPS drops occur more often this patch, and would like continued feedback about the problem. They also go on to explain what could be happening, "When we talk about performance, we usually focus on frametime, not FPS. FPS = Frames per second. Frametime = amount of time it takes to process one frame. We like to use frametime because it provides more consistent relative swings in performance. For example, a dip from 420FPS to 300FPS sounds dramatic, but in terms of frametime, you're going from 2.38ms -> 3.33ms (a one millisecond increase). Respectively, Going from 300FPS -> 140FPS is a 3.8ms frametime increase. We care a lot about maintaining smooth performance, so we don't want to see a lot of swings here, but 1-3ms deviations when activity is happening aren't completely unacceptable or unexpected."
And per Koalifier, they are aware of the worst map when it comes to FPS drops, "Seeing in the comments some mentions that Split is the worst offender on performance. We're aware and actively investigating it!"
Basically, the massive FPS drops you're seeing on your screen aren't indicative of what's actually happening, and you shouldn't be worrying about it.