When discussing performance-related topics, please always use objective, quantifiable "measures" instead of subjective, non-quantifiable "feelings".
Bad examples:
- The system was fast yesterday but much slower today.
- App reload takes too much time.
- System is not responsive enough.
Good examples:
- Opening an App took 5 seconds yesterday but today it takes 15 seconds to open the same App.
- App reload takes 2 hours to finish.
- Making a selection on a chart, it takes 30 seconds to show the calculation result.
Subjective, non-quantifiable "feelings" may be different from person to person but objective, quantifiable "measures" are more universal.
It would be much easier to communicate using numbers. So please make sure to provide them.