Sounds good. Do try upgrading to the latest patch of Spark Update 3 (12.4.15) or Boston (13.0.5) and let us know if the v2 composer begins to run faster.
Best practices for upgrading can be found in Upgrading Skuid on Salesforce. As a reminder, Salesforce does NOT allow reverting back to prior versions of managed packages. Skuid always recommends installing new versions in a non-business critical sandbox environment to test all mission critical functionality before installing into a production environment. We also recommend that you update out of date themes after you upgrade. Please let us know if you continue to encounter any problems with this issue after upgrading.
