HI Konstantinos --
Tableau Public is magic, but there are no switches we can throw on the server to speed particular dashboards up -- it's not that magic
How fast does the dashboard respond when you work inside the desktop client? Generally the response time you see in Desktop is a good measure of what your best performance on Server could be.
Can you point the community to a dashboard you feel is running too slowly?
It is responsive for me - what are your expectations around how fast it should be? Can you give me an example of something you'd do in this dashboard that seems slower than it should be to you?