So I had this problem when playing the game that caused constant stuttering when playing solo, like every 4 seconds, this problem ocurred when using "online mode" on Steam and didnt when using "offline", the solution is this: https://www.pcgamingwiki.com/wiki/Saints_Row_IV#Stuttering_caused_by_My_Steelport_service_shutdown look for "Stuttering caused by My Steelport service shutdown" and not forget to open th "host" file as administrator or You wont be able to save it. Apparently the game tries to acces same servers that no longer exist so it tries to reach them and fail. This solution was posted by nclok1405 on reddit so thank to him.