Hello,
the the situation in picture 1 shows a 'double connection' (two connections from the same edge to the same target lane.
The colors of the connections indicate that the rightmost lane has right of way and this forces vehicles which pass the gray connection to slow down.
In the second picture there is no double connection. Vehicles leaving the bus lane have to change lanes in order to continue. Consequently there is no conflict between connections a regular traffic does not experience slow down.
There multiple ways to fix your problem
1) remove the connection from the bus lane to the next edge (thereby forcing buses to change lanes in order to continue with their route)
2) change the right-of-way rules as explained here:
http://sumo.dlr.de/wiki/Networks/PlainXML#Multiple_connections_from_the_same_edge_to_the_same_target_lane3) use the latest development version of sumo and rebuilt your network. In the latest development version the right-of-way heuristic for double connections has been improved. In situations like these, the bus would have to yield and normal traffic would avoid slow-down.
