Convert duration that increases over time (public instance)

[ggrossetie]

I've noticed a strange behavior where the convert duration increases over time:

It does not seem to affect all requests. For instance, on the first screenshot, some graphviz and plantuml requests took a few milliseconds while others took more than a minute.

It does not seem to affect companion containers. Maybe we are hitting a process execution limit.

We might want to use https://github.com/brettwooldridge/NuProcess (or https://github.com/vietj/childprocess-vertx-ext) to improve the scalability.