Adalo’s servers are physically in the USA.
It takes time to ‘talk’ between phones/computers and the server. The farther away the longer it takes.
Africa seems to be on the ‘long’ side…
It really depends on how complicated your app will be (how much information it loads in one screen and how many interrelations between data you have).
Keep in mind that you certainly won’t reach speeds of custom highly optimised apps like Facebook, instagram etc, using a no-code tool like Adalo.
Simple apps will be fine, but you will have some waiting times in use. Make sure you make use of handy UX features like loading spinners to mitigate it a bit from user perspective.