Hana has inside differents engines that make the calculations on each step of the procces to obtain and show information.
SAP says that you can migrate your current BW content to hana, but in order to get performance improvements, is needed to tune the query bex. Because is possible to have a problems like this.
you need to see where is the bottleneck and attack it.
consider this:
1) Delegate all the calculations to the database level.
2) apply filters in the database level
3) only transfer results (see if you are having issues in your network)
4) what Hana database version are you using with? Investigate if you are using a new HDB system.
5) Hana has several traces inside that you can enable and investigate. look for some information and try to use it.
hope it helps.