Watcher is using a lot of so called TextTemplate fields in a watch
definition, which can use mustache to insert the watch id for example.
For the user it is non-obvious which field is just a string field or
which field is a text template.
This also means, that for every such field, we currently do a script
compilation, even if the field does not contain any mustache syntax.
This will lead to an increased script cache churn, because those
compiled scripts (that only contain a string), will evict other scripts.
On top of that, this also means that an unneeded compilation has
happened, instead of returning that string immediately.
The usages of mustache templating are in all of the actions (most of the time far
more than one compilation) as well as most of the inputs.
Especially when running a lot of watches in parallel, this will reduce
execution times and help reuse of real scripts.
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