Improve performance: Polls - MKR Responsiveness

[leolower]

https://docs.google.com/spreadsheets/d/1Afmf20_nvc-9qtmlSWUZMvrVGrh_Pj98oKiRxMEPF_U/edit?ts=5e7d2516#gid=0&range=B9:B11

How to test this

• Make sure the cache works in several different browsers, desktop and mobile (list TBD)
• Compare with mkrgov.science: MKR Responsiveness graph should look exactly the same