Shader comp leads to hanging/crashing specifically in incursions, w/related bugs (#402,754,333)

I've had this issue happen a few times before: running incursions has a habit to impact performance, and often major lag when trying to compile shaders for many effects, especially given that these encounters involve monsters & effects not found in normal mapping.

In this particular instance, I've seen a very specific, consistent abnormal behavior, where, upon generally scoring the first monster kill within an Incursion (often but not always the first Incursion encounter in a map) the game will hang: video will cease processing on a given frame, and the game will become unresponsive.

This hang is not permanent, but eventually resolves after 30+ seconds. Of course, under normal circumstances this will trigger the client's auto-disconnect before it resolves, which means that particular incursion encounter gets lost.

Worth noting that this can be averted (saving the encounter, as well as a map portal) by hitting the [esc] key early in this hang to bring up the pause menu. While it does not respond immediately, it will bring up the menu, and prevent the client disconnecting. If this is not done, the client will disconnect.

Regardless of whether the client disconnected or it was prevented by opening up the pause menu, the game's automap for that zone will be wiped, as well.

This report also centers around a particular incident where this disconnect was averted... But immediately afterward, the game fully crashed (to desktop) when attempting to talk to Alva afterwards.

When the game was opened again, it behaved as if the shader cache had been purged; excessive lag was on hand as it was constantly compiling shaders, and every monster, effect, even the terrain gradually "popped-in" over the course of the next few minutes, continuing through map completion.

• Bug Report ID: #402,754,333. This is almost certainly worthless (as it was only able to bug report after the hang, and this sort of data isn't included) but it is included to fend off bad-faith commenters.
  
  
• Reproduction: As best I can tell, this exclusively happens when compiling shaders for major effects (such as a screen's worth of monsters all dying on the same frame) the first time this happens upon entering an Incursion. Because this very much appears to be a shader-compilation issue, CLEAR THE SHADER CACHE BEFORE ATTEMPTING REPLICATION.
  
  Worth noting that this wasn't the first incursion of the map, let alone session/day. However, this case was the first one upon grabbing a Gloom Shrine. (which procs a chaos explosion on-death effect for monsters)
  
  
• Screenshot: Attached is a snippet from a screencap of the desktop while playing windowed: it shows the frame upon which the game froze. The in-game screenshot button does not work, since at the time the game is frozen and unresponsive.