Using Baikonur as a launch site, whilst you state it is efficient, this is all relative. The essentials to the uninitiated are that the closer to the Earth's rotational axis (this changes through the seasons between the Tropics of Cancer and Capricorn) you are, the less energy you need to launch.

Map Showing Global Rocket Laun... 

It's for this reason that the Russians also use the European Space Agency's space port of Korou in French Guiana (North Eastern Part of South America) to launch their Soyuz rockets. For the same cost in fuel, Soyuz can lift 1.8t satellite to Geostationary orbit from Baikonur, but 2.8t from Korou (or a large reduction in cost for the launch (usually in Millions!).

It is for this reason, a company called Sea Launch started using an Oil rig as a launcher, which is towed to the current rotational axis, saving money whichever season you are in.