How to optimize ui in ue5

Hi guys hope.you are doing great , so before asking my question let me tell you the whole thing . So I am making a racing game and I recently implemented umg ui in it . I made 2 levels , 1 for ui which has nothing in it and second one is the racing level where I have my map with landscape and cars setup but the landscape doesn’t have anything on it just material and ocean so what happens is that when I play my game directly from racing level I get about 70 fps and I have a speedometer widget which updates 30 times per sec and with the speedometer i get 70 fps but when I play my game from ui level first the splash screens show up and then the title ui in which I get about 100 fps then there is a option to either enter to go to main menu so when I go to main menu and then choose free roam to race on the map I don’t know.why I get about 55 fps and sometimes 30.fps.for a sec or two but not more than 60 fps . So I want to know is it because of the ui , if not then what can be the cause of such performance drop .

Thanks in advanced