Choco install wsl-ubuntu-1804 is slow

First of all, thanks for supporting WSL!
Other than creating a sudoer user (appveyor does that by default btw), adding new git.autocrlf/symlink flags and setting up WSLENV to pass on environment variables to WSL, there have been no hiccups! My config https://github.com/rokmoln/support-firecloud/blob/master/.travis.yml#L107-L133

I’m wondering if anyone knows how to speed up the installation of a distro though.
As per https://travis-ci.com/github/rokmoln/support-firecloud/jobs/360209818#L84 “choco install wsl-ubuntu-1804” took almost 4 minutes. 4 minutes on every run, is time wasted both for me, but also for travis.

Would it be possible to specify in .travis.yml that I need wsl-ubuntu-1804 on my image, and thus get a prebuilt image?
Thanks!