We pay attention to any performance related problem found by our users and try to fix them as soon as possible. If you ever face this experience again I strongly recommend you to report it immediately so we can reproduce it and provide a fix for you.
The Gradle support is a part of Community Edition. Code completion should be available for dependencies and plugins (available in the Maven central). I've seen a few cases when there were no completion for the artifacts from the local Android repository. It will be fixed shortly.
red error lines appears all the time in the template, despite being correct and compiling without error. A few recent encounters are text after @function are highlighted as unexpected token, a defined variable is not recognized, and reformatting sometimes breaks the template by doing actions such as converting documents.map { doc => ...} to documents.map { \n doc => ... }.
as it was commented below IntelliJ IDEA includes almost the same support (mostly the same) for other languages (PHP/Ruby/Python) as other IntelliJ-based IDEs. But at the same time IntelliJ IDEA never was positioned as a "true" polyglot IDE. IntelliJ IDEA is Java platform IDE, in the first place. It does support other technologies via plugins though, it might be much more convenient to use dedicated IDEs for other technologies.
