The number of projects has a minor impact on the performance.
The number of files has a linear impact on the performance, meaning, an operation on 5000 files will take about 5 times as long as the same operation on 1000 files.
Tip: An operation on specific files does not affect any other files in the Repository. An operation on a specific project does not affect files on other projects. Use project shortcuts to minimize user access to non-related projects. (see next FAQ).