Tchibo/O2 selectively throttling download speeds?

[inquisitor]

Originally Posted by RobF

Or could Tchibo themselves be responsible? Tchibo Mobil completely revamped their customer web interface about 2 weeks ago, and it is still incredibly buggy. Could they also have monkeyed around with broadcasting settings, or told O2 to do so?

It's possible that O2 does apply some sort of throttling but I've neither experienced nor heard from such so far.

Added twist: Tried some file downloads using network protocols other than http. In a file DL via bittorrent got a rate of 2 Mbit/s, in two different ftp DL's got 400 kbit/s (Knoppix distro DL) and 150 kbit/s (Index of /), resp. The very same files DL with two different web browsers (Firefox and Chrome, i.e. using http) were again crawling in at a mere 60 kbit/s. So it looks as though a continuous http DL is affected the most in this performance degradation.

These observations rather indicate that there is no intentional throttling since if they throttled protocol-based then bittorent would be the first service to be affected.

BTW, can I identify the location of the broadcast tower(s) that serve my cell and get their usage statistics?

You can locate the basestation (or "nodeB" as it is called for UMTS) by finding out its MCC (Germany: 262), MNC (O2: 07), LAC and CellID and then looking it up it one of the many geolocation databases (see mobile - Public Cell ID databases - Stack Overflow).
A pretty straightforward method is to use Google Maps on your smartphone, on which you would disable WiFi and GPS - then localization is performed only by the cellID, which will result in a rather large blue circle shown on the map, which is the estimated coverage area of your serving cell. The tower itself is usually located somewhere close to the edge of this blue circle as it uses sector antennas covering a 120° angle from its location. Once you get a rough idea of where the tower is situated, check the regulatory authority's map for potential tower locations. If requested the regulatory authority does provide the approval documents ("Standortbescheinigung") for the desired location, which reveals the tower configuration (operator, each single antenna including direction, used radio technology and frequency).
But you won't find any load statistics - that's proabably one of operators' greatest secrets.