The warp cruising speed used to be warp 6 but has now changed. About four or five years ago the Enterprise-D found that warp travel can be hazardous to space. Keep in mind the damage done is very little but as areas of space are traveled more the damage builds. The new cruising speed is now warp 5. This won't stop the damage but will slow down the damage. Some groups are trying to get it reduced further but it would slow down ships to much. Unless new evidence is presented the warp cruising speed will remain at warp 5.