Have you considered moving the compiler to the client side? In theory you can build a C/C++ and virtually any other language compiler in Javascript.
Security restrictions on the browser might be an issue, but i think you should be able to store the binary output in the local storage and upload it to the server.
The drilldown is roughly:
* $5K Amazon + mLab hosting
* $3K extra services (intercom, mailchimp, dropbox, gmail, slack etc)
* $1K accounting/payroll overhead
* $1K all office expenses
* $15K salaries
people underestimate the cost of compilations for 10,000 people. We have ~150,000 compilations per month ;)