You are underestimating how much processing power you need for a smooth experience using IntelliJ, even without compiling anything :P
I also have a 16G 2015 MBP running Monterey and IntelliJ with no problem at all though.
On my M1 Max MBP Jetbrains Rider stars in under two seconds. Loading the quite large project takes another two.
On my previous laptop, an i7 MBP, it took in the order of minutes to get Rider to the point where I could actually start writing code with codecompletion. It sounded like a jet taking off while Rider blasted all cores at max to enable the smart completions.
The M1 Max isn't even slightly warm in the same case. Haven't found out a single spot where it would've even slightly stuttered.