How to compile sourcemaps only after compiling less?

There is a style.less for 10k lines , and its compilation in css with sourcemaps , which takes ** 10 seconds (shortly, and without sourcemaps 1s) . Is it possible to optimize this by sequential compilation?

i.e:

1. Скомпилировать style.less в style.css; 2. После, cкомпилировать его style.css.map;