Too Much Time at Node 0
For some problems, ILOG CPLEX will spend a significant amount of time performing computation at node 0, apart from solving the LP relaxation. While this investment of time normally saves in the overall branch & cut, it does not always do so. Time spent at node 0 can be reduced by two parameters.
First, you can turn off the node heuristic:
Second, you can choose a less expensive variable selection strategy:
Time at node 0 can also be consumed by the effort to solve the LP relaxation. Experiment by solving the relaxed problem using each of the LP optimizers. These experiments may suggest a better setting for the startalgorithm parameter.
