Borland Pascal had built in assembly which was very easy to use and integrated with the rest of the language. This let me have DOS program that had it's own high performance graphics for GUI (I basically stole Motif visual design with some adaptations) and proprietary preemptive multithreading. C programs venturing into same realm were not really any faster and had to use assembly anyways for performance critical parts.
To share a similar anecdote I was so proud of myself having created my own mouse support unit, that I then used to plug into a couple of BGI based applications.
Indeed it did, and it was magic. Just an asm: declaration and off you went, kitchen sink and access to variables included. I wrote some fairly nifty graphics stuff that way in the early Delphies, mid to late nineties. Great fun, still miss it.