Limit on Number of Recrods to Update / Insert

Hello,  

We are integrating the following data on a nightly basis. At present, we update / insert 10 records at a time for each webservice call. Want to know the maximum limits to perform such operations without affecting performance -  am looking at avenues to possibly reduce the time taken when the data volume is large. 

Following are the entities we update or insert into our CRMOD pod.

1) Contact

2) Opportunity 

3) Opportunity Reveune 

Thanks and Regards,

-Sooraj