That is normal. Run a "Working" filter. Use mame -listxml or your frontend to exclude non-working, mechanical, and adult games.
MAME is struggling with CPU performance. Go to Video Options and enable "Throttle" or reduce audio sample rate to 22050Hz.
A true "Full Set" often comes in two parts: the ROMs set (relatively small, around 40-40 GB) and the CHD set (massive, often exceeding 500 GB to 1 TB). How to Manage and Clean Your MAME Full Set Mame Full Set Roms
The Ultimate Guide to MAME Full Set ROMs: Everything You Need to Know
An absolute full set includes thousands of unplayable casino games, mahjong titles, and foreign-language quizzes. Running a frontend like LaunchBox, CoinOPS, or RetroPie with an unedited full set can make navigating your library a nightmare. That is normal
: Audio files for older games that used analog sound hardware which cannot be easily emulated through standard ROM data.
If you decide to assemble a full set (either legally via self-dumping or by acquiring them from private archives), here is the workflow. MAME is struggling with CPU performance
The standard collection containing the game code and graphics data for thousands of titles. CHDs (Compressed Hunks of Data):