How to find sections of code where there is a big delay?

Question

PHP

Hi all.
Such a situation: I take data from the database and generate an Excel report on it.
The report affects: 60,000 cells.
I load all the data with 3 queries into the database and save it to an array.
The report is generated in ~280 sec = ~ 5 min
How can I check where in my code I have the biggest delay?
Server :

• Ubuntu 14.04 x64
  
• Apache24
  
• PHP7.0
  

Class for generating Excel files PHPExcel

Answer 1

Thank you guys for your attention.
Solution : I removed all the styles that I created for the pages, and after that the report was generated in 9 seconds.
Decided not to bother with the design yet. Since the extra 270 seconds is a lot

Answer 2

1. Make a report not in PhpExcel, but simply in HTML.
2. If it takes a long time, check the logic by inserting a microtime check.
3. When you get a quick report output, save this HTML to an XLS file and don't mess with any ugly formats.