Long start up period in case of too many testcases

#### What are you trying to achieve?
Pause between codeceptjs run command and first scenario steps execution should not spend seconds, tens of seconds

#### What do you get instead?
In the case with a lot of test files and scenarios into these files I see initial delay in ~40 seconds . Related with ~70 feature.ts files and ~400 scenarios.
Who knows, it can be related with initial reading of files with tests and can be related with node_modules/codeceptjs/lib/mochaFactory.js and mocha.loadFiles...
In case of project with small count of files and scenarios delay < 2-3 seconds.

> Provide console output if related. Use `--verbose` mode for more details.

```bash
make test-e2e GREP=@debug
yarn codeceptjs run --steps --verbose --grep=@debug
yarn run v1.22.10
$ XXX/node_modules/.bin/codeceptjs run --steps --verbose --grep=@debug
{
startUrl: 'http://localhost:9000',
tests: 'XXXX/**/*.feature.ts'
}
```

### Details

* CodeceptJS version: 2.6.11/3.0.4
* NodeJS Version: v12.19.0
* Operating System: MacOS 10.15.7
* puppeteer