Comment by WizardClickBoy

Thanks! Gippity did suggest the xargs approach as an alternative, but I found that

find [...] - exec [...] {} +

as opposed to

find [...] - exec [...] {} \;

worked fine and was performant enough for my use-case. An example command was

find . -type f -name "*.html" -exec sed -i '' -e 's/\.\.\/\.\.\/\.\.\//\.\.\/\.\.\/\.\.\/source\//g' {} +

which took about 20s to run