Well, seeing Your specs, i guess you don’t have anything to worry about. The myth goes “installing stuff slows down your pc”. That is partially true on windows. But on linux, you can install EVERYTHING without any performance issues. Because there are thousands of servers installed with thousands of packages. You won’t have ANY issues. If you don’t believe me, try it. Now I think you now believe that it won’t make any more performance issues.
Now for the term " instability", I don’t Think you will have any issues. You “could” have issues having multiple versions of C/C++ compilers as packages could get confused which compiler to build with. But as almost no packages are compiled with haskell, your haskell installation will stay safe and out ofyour way. But of course, you will have “temporary” sluggishness when compiling large applications. Other than that, you won’t have any issues.