PHP, MySQL: debugging, stability, performance enhancement and upgrade

BACKGROUND We have a three-tier application that was launched in 2013 but shelved in 2016. It runs on AWS EC2's, ubuntu 12.04 + PHP 5.3.10 + Zend 2.3.0 + MySQL 5.5.32 (now out of date). We have looked at restarting it and refreshing it but have found some issues (the original development team has since dispersed). REQUIREMENT / DELIVERABLES We are looking for a reliable team or person that can: 1) Review the existing code and determine the reasons for why it now runs so slowly (this should NOT require code change, it must logically be a configuration issue). Must be able to get the average response time to under 1.5secs (as it was previously). 2) Review the existing code-base and look at how best to upgrade it (ie. PHP, MySQL), then complete an upgrade (longer term goal) This requires an analytical team with a solid understanding of older PHP/MySQL/server configuration. Sloppy lazy coding/fixes, or people who take shortcuts are not welcome. Each delivery will need to be fully documented with a list of before and after changes. Step 1 should be relatively quick for an experienced system admin/developer. Step 2 can be spread over a longer period and may require further discussion. Completion of all steps to a high standard with a high degree of professionalism will result in a longer term contract for ongoing maintenance, enhancement and upgrade. PAYMENT Targets and fixed payments will be agreed on a time and materials basis for each phase, and will not be paid unless targets can be validated. Failure to deliver to target or by deadline will result in the contract being terminated with no payment. Partial delivery of a step by definition is not a working delivery. There will be no payment for partial delivery under any circumstances. MINIMUM SKILLSET Preference will be given to those with experience in professional working environments (eg. large multi-national companies, banks, tier-1 technology companies etc). 1) Do not apply if you do not have experience in the above, or if you are an amateur. 2) Do not apply if you have a project completion rate below 95% 3) Do not apply if you have a rating below 4.5 4) Do not apply if you are unreliable