I guess they throttle speeds for this tariff, as the network obviously can deliver much more.
No idea how their LTE network performs (I still don't have any LTE handset), but I doubt they admit prepaid SIMs to their LTE network and furthermore swisscom is currently deploying LTE only to LTE band III (1800 MHz) which does not improve signal propagation significantly over UMTS band I (2100 MHz). As usual the bottle neck is probably the backhaul which is shared by the NodeB and eNodeB. So I wouldn't expect too much improvement from LTE.
Btw what handset are you using? Many handsets only support receive antenna diversity and MIMO for some of the supported UMTS frequency bands, which results in subpar performance on those secondary frequency bands. Unfortunately few manufactureres disclose for which frequency bands their phones support diversity. E.g. Motorola Germany states that the European Razr i supports RX diversity only for UMTS2100 and UMTS900, despite it also supports UMTS850 and UMTS1900 (
Motorola RAZR*i*? Intel®-Prozessor*? Kompaktes Design - Motorola Mobility LLC. Deutschland). So if you have an American handset it probably doesn't support RX diversity for UMTS2100 and thus will deliver less bandwidth especially on the cell edge.
You can easily top up your SIM by credit card even without having access to their customer portal:
https://www.swisscom-mobile.ch/scm/p...fladen-en.aspx