The performance is based on the features of the phone like CPU speed, RAM etc.
And of course it depends on the internet speed too.
The HWC applications are meant for light weight applications (Approval scenarios). It is based on the web browser of the mobile device (HTML). So it can't handle if a large amount of data need to be pulled from the SAP server.
If the business scenario is complex go for native apps,performance will be high for it.