Hi Mohammed,
LSO was designed for throughput improvement so disabling it is not recommended, unless we have determined a pathology requiring a disablement. There are some articles on the site which show this phenomenon in combination with peer LRO causing degradation in throughput (
http://blog.delphix.com/seb/2013/03/15/lso/), hence, we need to determine that this is required and even then this is not the final solution.
In your case, you need to get in touch with support to determine root cause of low throughput. Also, if needed, to actually disable it on the engine you will need delphix support.