New strings will take a few shots to stabilize. Some may take 200 shots. Generic strings like you usually find at any shop, including Zebra strings, will creep forever. I don't think it can be narrowed down to the material they are made of, because many aftermarket string makers use the same stuff the factories do. It's just that they have superior procedures for prestretching and pretwisting and serving under pressure. MOST, but not all, factory strings and their generic replacements are put together quickly with basically one goal in mind---hold things together.

Now I'll ask how many twists are in the string you have. Good aftermarket strings such as Winner's Choice have about one complete twist for every 1 1/2" of length. A string that is twisted correctly will distribute the load over the strands more evenly and stabilize quicker. There is more to it, but suffice it to say that yes, you get what you pay for. With Zebra strings being the exception.

Here's a suggestion. PM Gibblet on this site and order a set from him. I'm using a set from him and find they compare very favorably with Prostrings and Winner's Choice that I have also used, except his prices are very reasonable.

After you get them and they are installed shoot about 50 shots through them and then install a peep sight. And one like the Fletcher Hunter Mag with 1/4" hole. Pretty much your peep rotation will go away altogether.

And besides, you can pick some pretty colors like pink and purple. LOL.