Tap a Windows 10 Mobile app, then go back to the home screen. Chances are you’ll see an annoying “Loading...” message. But with Microsoft wrapping up work on the desktop version of Windows 10, look for the fit and finish of Windows 10 Mobile to improve soon.

Greg Sullivan, communications director for Microsoft Devices, explained that because Microsoft’s development teams are all working on the same operating system, Windows 10, they can be more easily reallocated to add features or squash bugs. “In early to mid July...a lot more attention will be shifted from this [Windows 10 desktop] to that [Windows 10 Mobile],” Sullivan added.

Why this matters: Microsoft won’t say when we can expect Windows 10 Mobile to ship, whether it’s September or sometime sooner. But some have begun to worry whether Microsoft can hit its release dates, with two major operating systems to complete and polish this summer and fall. Once July 29 arrives, expect a number of Windows engineers to jump in the fountains in the Redmond campus, Sullivan said. Soon, however, it’s going to be back to work to make sure Microsoft’s mobile OS ships on time.

A fast OS is a finished OS

Windows 10 Mobile is still rough, no question about it. Recent builds have helped it along, but the software still stutters and groans here and there, and Microsoft still recommends that users install it on a spare phone rather than their everyday one. Worse still, Microsoft also confirmed this week that Jo Harlow, the corporate vice president who oversaw Microsoft’s phones business, has left the company as part of a recent reorganization.

There are signs of hope, however. May’s Windows 10 Mobile Build 10080 was Microsoft’s first that felt like a true smartphone OS, rather than a development platform. But it was Build 10136 that highlighted the discrepancies that Microsoft needs to work to overcome: The Cortana search function responds immediately, with snappy responses, but the rest of the operating system feels sluggish by comparison.

Let's face it:, though: Microsoft has its work cut out for it. One Windows team might be able to overcome a history of running third in the smartphone market. But it's going to need to polish the OS enough to convince those testing it to, in turn, persuade their friends and family to sign on to Windows 10 Mobile.