As @JDRoberts stated above, not much has changed since the time the v2 hub was originally released when it comes to SmartApps that can run locally. Lots of devices are now local, including some virtual devices that come in handy from time to time.
If local processing is a high priority for you, there are some other options available now on the market. One platform, released back in February, was designed and developed by some of the most prolific SmartThings Community members. As such, migrating from ST to this platform is relatively simple, as it also uses Groovy for custom code.
Here’s the ongoing thread regarding this newcomer to the market.