The macroinstruction file MusicTEX contains approximately 2500 lines of code, that is 80 000 bytes approximately. This requires your score to be compiled by the most extended versions of TEX (65 000 words of working memory). In desperate situations, we recommend using the ``BigTEX'' processors which, unfortunately, perform a great deal of disk input/outputs (on PCs) which make them awfully slow.
In particular, the number of registers it uses can hinder its compatibility with some LaTEX styles or with LaTEX itself in case of restricted memory availability.