Your error log does include a couple memory limit exceeded errors. The message swamping the rest of your logfile originates from your custom theme; you might consider fixing those instances just for the sake of cleaner logs.
We’ll do some poking around on our end but there’s a certain extent to which the new Mapping is going to be somewhat more memory-hungry because it allows for arbitrary geometry and not just points, so the representation of each simple point is not as small as it used to be.
For the time being, you have the alternative option, subject to your ability to set server settings, of increasing PHP’s memory_limit setting to allow for larger mapping “pages.”