Personally, it slows me down considerably without intellisense, even when I know the entire codebase. If you have overloaded methods, for example, just remembering the order of the parameters is impossible without intellisense.
This makes me believe that either I have a really poor memory by not being able to memorize thousands of method names, their parameters and orders or other devs have a really, really good memory.
You're not alone. I strictly use kwargs in my functions because I can't be arsed to remember the order of arguments in addition to the structure of the rest of the program. It's more work but I need any simplification or hint I can get for my feeble mind. And I don't even use Java.
This makes me believe that either I have a really poor memory by not being able to memorize thousands of method names, their parameters and orders or other devs have a really, really good memory.