Worlds crash within minutes of loading.

Problem:

Single-player local world will (usually) load, and play with variable levels of lag from severe to barely noticeable.

Minecraft then crashes out to desktop with "Java(TM Platform SE binary has stopped working" within 1-3 minutes of loading. Has been fine until about a week ago, but now occurs with both newly generated and pre-problem worlds.

Attempted solutions:

Double RAM allowance in launcher profile parameters. Result: No effect.

Uninstall Java Update 90: Result: No effect.

Uninstall and reinstall Java completely, using version linked to on Minecraft website. Result: No effect.

Install non-Java launcher. Result: No effect.

Halve view distance, drop graphics from "Fancy" to "Fast". Result: No effect.

Attached:

Screenshot of launcher log (shows lag), error message re: Java, and Windows System Info panel.