Once it's finished indexing things it feels darn instant to me. What hardware do you use? Also which programming language? I've used IntelliJ with Java, Scala, Kotlin, Groovy, Markdown, and many file types and it's really snappy.
That is actually a misconception. You may have this mental classification of Java as a slow language if you looked at its performance 20 years ago. Now it's actually really fast, it goes neck to neck with C++. Sure, Rust or Go or C (or definitely assembler) might be faster in some workloads, but Java is definitely very very fast nowadays. It uses a lot of memory because of the way Garbage Collection works, but it is fast. It's definitely faster than Python, Ruby, PHP and many other kids on the block...