For me it´s not slow in comparison with other scopes here.
Good, other scopes here are older Waverunner models, some Wavesurfer models.
Compare it with them the rigol is even "better".
But what means "slow" in this case…Do you really need a fast responsive FFT...
Apart from this, althoug the tests are not fully done yet, I think about buying the options bundle.
Hacking is a nice thing but ruins your warranty, ruins the reselling price.
And only buying the options bundle, the bandwith upgrades are too expensive and in my case actually unimportant.
A MSO 5074 with options bundle costs about 1800€ - I don´t know any scope which can beat the overall-performance at this price.
If rigol fixed the issues and add some nice to haves, it will be a killer.