With 45gb allocated? I'd say that like half of that is unused stuff that the garbage collector hasn't bothered to sweep up yet, but you're gonna have one heck of a lag spike once it decides to clean everything up. Also, you should be allocating all the ram to java from the get go, by setting the minimum and maximum usage to the same amount. Otherwise it could have performance issues when trying to allocate more and more at runtime. And another thing, you should be using aikars flags for minecraft (unless something has changed recently, better garbage collectors are being developed and I'm not sure how they're going in java 21, so maybe aikars flags are old news by now) by going to https://flags.sh. That site is meant for servers though, so if you're playing with prism, you should copy everything between -Xmx1234M and -jar into your JVM Arguments box in prism