https://english.stackexchange.com/questions/543934/word-for-software-with-a-large-size
Bloatware, memory hog, or Monolith – what do you call software that is the opposite of lightweight?
You can use bloated as a somewhat loaded term which is also a bit ambiguous: it may indicate software which takes up a lot of disk space, is memory-hungry, and/or works slowly. It may also suggest there are too many features or that they are cumbersome to use.
More technical (and also more specific) terms include: software with a big disk (or memory etc.) footprint and resource-intensive software. On a more generic note, you can say the software is demanding (though without any context, it may not be clear if it’s demanding of the computing resources or of the user).