Your browser will display a low memory error if your cache is full. To disable this error, simply disable the use of your cache by changing the settings. The disadvantage is that each page will need to be loaded as it will not be stored locally.
You can increase the size of your cache, but in the end, it will cause the same problem. For the time being, it is best to disable cache. Hopefully Sony will release a fix for this error!
If the error persists, you can manually empty the cache. The error normally occurs when you try to load a large page or image.
Firmware 3.10+
On Firmware 3.10 and greater, you can enable the [Conserve Memory] option from the[View Settings] menu to prevent the Low Memory Error from occuring. The [Conserve Memory] option enables you to view a Web page that contains a larger amount of data because less memory is used to display the page.