All mounts have the same speed. This includes normal Mounts, shiny ones, Jet Skis or Legendary Mounts. The only Mount that is slower than the other ones is Wailmer Mount.
Why don't you try to beat e4? Train your mons in victory road. Once you complete story you'll get access to all areas ( some requires ms and quest walkthrough ). You can hunt anything later then. BTW spawn are better then what they were in past.
Just find a better place to farm ? Use repel trick ? If you're looking for a usable feebas it can take you days. A MMO is supposed to be more challenging no?
This is a RNG based game and it's just your RNG. Feebas is a very rare Pokemon + every Pokémon in map changes chances for encountering a rare mon. You may feel like there is no feebas spawn.
Shiny chance in game is 1/8k but you don't really encounter them after 8k encounters.