Fix typos

Update performance.md

Author: joeyates

docs/performance.md

@@ -1,14 +1,12 @@
-# Performace
+# Performance
 
-The two performance-related settings are "Download strategy",
-which is a global setting,
-and "Multi-fetch size", which is an Account-level setting.
+The two performance-related settings are "Download strategy", which is a global setting, and "Multi-fetch size", which is an Account-level setting.
 
 As with all performance tweaks, there are trade-offs.
 
 # Overview
 
-The defaults, which suit most machines and plays nice with servers is:
+The defaults, which suit most machines and play nice with servers are:
 
 * Download strategy: "delay writing metadata",
 * Multi-fetch size: 1.
@@ -18,7 +16,7 @@ a small virtual server or Raspberry Pi
 to run your backups, you can change "Download strategy".
 
 If your email provider supports it,
-and you don't have tight memeory limits,
+and you don't have tight memory limits,
 increase "Multi-fetch size" for faster backups.
 
 # Delay download writes
@@ -45,7 +43,7 @@ By default, during backup, each message is downloaded one-by-one.
 Using this setting, you can download chunks of emails at a time,
 potentially speeding up the process.
 
-Using multi-fetch *will* mean that the backup process will use
+Using multi-fetch mean that the backup process *will* use
 more memory - equivalent to the size of the groups of messages
 that are downloaded.