Document troubleshooting for memory leaks and getting profiles

docs/memory-profiles-and-leaks.md

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+## Memory leaks
+
+Riot usually emits slow behaviour just before it is about to crash. Getting a 
+memory snapshot (below) just before that happens is ideal in figuring out what
+is going wrong.
+
+Common symptoms are clicking on a room and it feels like the tab froze and scrolling
+becoming jumpy/staggered. 
+
+If you receive a white screen (electron) or the chrome crash page, it is likely
+run out of memory and it is too late for a memory profile. Please do report when
+this happens though so we can try and narrow down what might have gone wrong.
+
+## Memory profiles/snapshots
+
+When investigating memory leaks/problems it's usually important to compare snapshots
+from different points in the Riot session lifecycle. Most importantly, a snapshot
+to establish the baseline or "normal" memory usage is useful. Taking a snapshot
+roughly 30-60 minutes after starting Riot is a good time to establish "normal"
+memory usage for the app - anything after that is at risk of hiding the memory leak
+and anything newer is still in the warmup stages of the app.
+
+**Memory profiles can contain sensitive information.** If you are submitting a memory
+profile to us for debugging purposes, please pick the appropriate Riot developer and
+send them over an encrypted private message. *Do not share your memory profile in
+public channels or with people you do not trust.*
+
+### Taking a memory profile (Firefox)
+
+1. Press CTRL+SHIFT+I (I as in eye).
+2. Click the Memory tab.
+3. Press the camera icon in the top left of the pane.
+4. Wait a bit (coffee is a good option).
+5. When the save button appears on the left side of the panel, click it to save the
+   profile locally.
+6. Compress the file (gzip or regular zip) to make the file smaller.
+7. Send the compressed file to whoever asked for it (if you trust them).
+
+While the profile is in progress, the tab might be frozen or unresponsive.
+
+### Taking a memory profile (Chrome/Desktop)
+
+1. Press CTRL+SHIFT+I (I as in eye).
+2. Click the Memory tab.
+3. Select "Heap Snapshot" and the riot.im VM instance (not the indexeddb one).
+4. Click "Take Snapshot".
+5. Wait a bit (coffee is a good option).
+6. When the save button appears on the left side of the panel, click it to save the
+   profile locally.
+7. Compress the file (gzip or regular zip) to make the file smaller.
+8. Send the compressed file to whoever asked for it (if you trust them).
+
+While the profile is in progress, the tab might be frozen or unresponsive.