2👍
mod_wsgi starts two processes that run your Django program (actually these two processes are your Django program). When a request finishes, the process continues to run, being ready to serve a new request.
The request you are referring to needs 80 MB of memory, so Python requests that amount of memory from the operating system, and the operating system gives it to Python. When the request finishes, most of that memory is not needed any more, and it is unused. However, Python does not release it to the operating system. When Python needs memory again, it will re-use these 80 MB. In most cases, this way of working is satisfactory; it’s not a problem that Python does not release the memory, since it’s going to re-use it, so normally you don’t need to do anything.
inactivity-timeout makes mod_wsgi restart the process after 60 seconds, so the new process has not yet served a request, so it’s not consuming any significant amount of memory.
See also Releasing memory in Python.