According to Wikipedia, Standard Deviation "is a measure that is used to quantify the amount of variation or dispersion of a set of data values."
In performance testing context, it give some information about the consistency of the response time (RT). In your example, the average RT is 145, and Std Dev is 7.8, this means that 67% of the time, the RT was in the range of 141 and 149. (avg - SD/2, avg + SD/2) This is relatively consistent, when compared to some of your other data samples (example, that first one has a pretty wide range).
For performance testing, I prefer to use either the median, or better the 95th percentile point to characterize the performance. I find it easer to say "95% of our users see response within 16 seconds" rather than "the average response is 6.3 seconds with a Std Dev of 8.3 seconds" The former statement is usually easier for a wide range of stakeholders to understand.