Latency issues with omnisphere and Reaper why?

[QuinnX]

Purchased reaper and feel its a realy good editor..
However i dont understand why i have latancy issues with omnisphere on a dual core 2ghz 4GB system..

I have ran omnisphere as a stand alone in a vst host and it works like a dream even in stack mode..
but when i load in to Reaper there is latency everywhere and its the only plug in running..

is it a failure of reaper or is there some unknown setting i need to get to?

Any help appriciated

[hopi]

you have not mentioned what you audio set up in reaper is:

are you using ASIO? what is your audio card? what are the sample rate settings on the card and inside reaper?

[QuinnX]

Im using a roland Fantom G6 as my ASIO and i get snap crackle and pop.. issues when using reaper... but surprisingly no issues with a stand alone vst host..

[hopi]

and in reaper pref's ...what are you settings for it?