Split Vector is taking too much time in mongo shard
The splitVector commands are slow because your system is slow, it's not the cause of the slowness itself - it just happens to be running frequently and hence is showing up a lot in your logs - it is a symptom not a cause (unless you are running many, many mongos processes and hitting an edge case).  People often make the same mistake by misdiagnosing slow serverStatus commands (run every 60 seconds by MMS monitoring) as a root cause.  

Usually the slowness is because your system is oversubscribed and hitting a bottleneck somewhere, but you have not provided enough information to make a guess as to what your issue is.  I would recommend looking for other evidence in the logs as well as the usual suspects (IO, CPU, Memory) to narrow down the actual root cause here.