Code more efficiently to avoid 'Apex CPU time limit exceeded'

What's counted

• All Apex code
• Library functions exposed in Apex
• Workflow execution

What's not counted

• Database operations, e.g. DML, SOQL
• SOSL
• HTTP callouts

Using Map based query

Map<id,account> aMap = new Map<id,account>([Select Id,Name from Account limit 50000]);

Explore if your business allows you to do the operation asynchronously

chance to make code execute in @future 

Aggregate SOQL usage

using SUM,AVG aggregate functions at the database

Only take necessary data and run a loop

This is essential now to filter only specific data while doing a for on a list of records as too much looping will increase CPU time