When was the last time you used Galaxy? Before 2.0? I will admit that it wasn't good before 2.0. It works very well since 2.0, and if it is more 'resource intensive' than other clients, it's not by any noticeable amount.
This is coming from someone that has 400+ games on steam(100+ installed), a bunch on epic because of free/endless coupons during sales, and a couple dozen split between all the on the other platforms. It takes no time at all to load a list of all the games I own. It does, of course, take a few seconds to launch a game from another client when that client isn't running, but that should be expected.