Why does the "monospace" font look great in Terminal and gedit, and terrible in IntelliJ IDEA?
I have the same problem. Apparently its a problem with the "hinting" level of the font, which IntelliJ forces to "full" no matter what the OS selects. This makes the fonts look jagged and thin rather than how its supposed to. There was a workaround I saw on a website, but it didn't work for me.
Generally, all Java software has poor font rendering under Linux. You’ll see this also under Windows, the fonts look different. It’s not a IntelliJ IDEA problem, but Java’s.