Currently all OData responses are send in plain text (no compression). In case wide data entities (with large number of fields) the response sizes can be large. Further more if paging takes place there are multiple responses send over the net.

Implementing compression (gzip, deflate) in Odata responses would shorten the transfer times.
Please note that compression is an option so enabling it would not influence currently working interfaces.

The general idea of compression in OData was described for example in the following post:
https://www.hanselman.com/blog/enabling-dynamic-compression-gzip-deflate-for-wcf-data-feeds-odata-and-other-custom-services-in-iis7