improve performance of Xpress interface and fix bug #678
| Job | Run time |
|---|---|
| 1h 4m 19s | |
| 1h 7m 21s | |
| 1h 17m 1s | |
| 1h 12m 58s | |
| 57m 15s | |
| 1h 3m 38s | |
| 1h 8m 11s | |
| 1h 3m 16s | |
| 54m 20s | |
| 58m 3s | |
| 1h 6m 31s | |
| 1h 0m 33s | |
| 57m 1s | |
| 1h 3m 11s | |
| 1h 6m 59s | |
| 1h 1m 29s | |
| 51m 53s | |
| 55m 19s | |
| 1h 4m 37s | |
| 57m 59s | |
| 50m 34s | |
| 54m 16s | |
| 1h 5m 23s | |
| 57m 16s | |
| 49m 53s | |
| 53m 48s | |
| 1h 0m 37s | |
| 55m 11s | |
| 1d 4h 18m 52s |