I can’t say if you will definitely run into the same problem. I can say that I have some pretty big sites that I maintain that use ACF extensively and some of the things I’ve created have hundreds of custom fields that ACF manages. This usually requires me to bump up the maximum memory limit for the site. (php ini setting memory_limit)
I can tell you that for each field that that is saved for a post that ACF creates 2 rows in the postmeta table. One for the value of the field itself and one that tells ACF how to treat that value. So it you have a field group with 100 fields then at a minimum ACF will create 200 rows. Some special fields like repeaters will create 1 row for the repeater itself and 2 rows for each field in the repeater.
