Currently we have one restlet in 1.0 that's taking 40-50 seconds to execute completely. Based on condition at worst scenario 5 searches are being performed, few fields in 1 customer record and 60 project records are getting updated. Will moving to 2.0 will make significant difference in response time or not?

[...]significant difference in response time" - Highly unlikely, why would you think it would?

Didn't. That's why wanted to make sure if it will..

Further to that, you may find an increase in performance using the query module rather than search. You may be able to reduce your searches by combining them with joins although that's not a straight swap to 2.0. 😉

You can try using nlapiSubmitField / record.submitFields instead of loading/saving record if you aren't already

Query Module implementation soon. code will need to be restructured slightly. Thank you for clearing the concern. Already using nlapiSubmitfFeld