The 139.68MB Logic Express 9.1.3 and 193.01MB Logic Pro 9.1.3 both primarily list improvements involving Hyper-Threading, an Intel technology that allows for the creation of virtual processors. The Express update improves compatibility with Hyper Threading while the Pro update fixes some problems related to Hyper Threading support.
In addition, the updates also fix a number of other bugs, including several that manifested in the previous 9.1.2 update, among them: an unexpected quit when using the Native Instruments Kontakt 4 Memory Server, a situation where a pair of Pedalboard stomboxes (“Classic Wah” and “Modern Wah”) stopped responding to mouse input, a bug where Logic would open fewer audio processing threads on i7 Quad-core Macs than in 9.1.1, and an issue where flattening and merging a Take Folder could result in an empty region due to a soloed track. There’s also a patch for an issue where Logic could stop resonding during launch due to the use of the TouchOSC Control Surface plug-in while Objective Development’s Little Snitch was set up to deny Logic network access.
Both updates require Mac OS X 10.5.8 or later and can be downloaded from Apple’s support downloads site.