thanks TheSqlGuru for your reply.
We dont use auto update. And is hard to find a "slow/off time" .. you know. We are thinking the best way to schedule to run in spare time.
In our server test takes 14 hours to complete the job. (less resources and almost the same database size)
Do you have Maintenance Jobs on your databases? That may fix the root cause of your problem, which like other already explained, it's because staled stats.
Take a look on this link: SQL Server Index and Statistics Maintenance
That's my favorite smart Index solution. It runs weekly and keep Indexes and statistics up to date. I like Ola's solution because it's "smart" means, if the table does not have enough pages or looks ok, the job will skip it and won't touch it.