Their 5G is at 4G speed. No other telco companies do that. Quick jump, what are you waiting for?
Simba 5G only use n1 with 10MHz.
Compared that with Singtel / Shared M1+SH 100MHz in n78, there is totally no contest.
Until / unless Simba get more spectrum for 5G, that would not improve.
And it would be fair to say that Simba's 5G is only for show in its current state.
The bigger puzzle is with Simba's 4G, where they have 60MHz, mainly in B40 (40MHz).
Compare that with Starhub 70MHz, Singtel 75MHz, M1 45MHz, I would say Simba is not at a disadvantage as for as spectrum is concern, so it does seem a bit strange why Simba's 4G performance is not good.
A possible explanation is that users are not able to make use of B40 which forms the bulk of Simba's 4G spectrum, which no other SG Telco uses, but that didn't make sense since my 10year old phone also supports that band.