I had the LG 42LA620V for a few years, and have now had the 42LB650V for about 2 years. No matter which OS/software version, you'll get Out of Memory errors. Occasionally I'll reset to factory settings to see if more stable than latest Software Update but generally you're better keeping latest version.
The memory errors occur in iPlayer, YouTube, and pretty much anything in the WebOS/Smart menu options. Some days the apps are unusable. Recent examples that come to mind; Last week YouTube crashed about 15 times in one day, and today iPlayer crashed 5 times in a short period before I gave in trying.
I have fast home networks, using wired connection rather than WiFi, and in terms of internet on a reliable "75Mb/s" connection.
I like the LG TVs function and design, but having spent years with Out of Memory errors, will not be buying LG for my next TV.
Note that this is purely my own experience and opinion. Other people no doubt have different experiences and opinions. I'm simply sharing my experience to empathise with everyone still having this problem.