Transferring a self-written site to a CMS?

Question

CMS

There is a large information portal that has been operating since 2004.
The site is written in Perl. Traffic 50,000 per day.
I want to change the design and at the same time put on the engine.
Can you please tell me which engine to choose or at least which ones to look at?
How does moving to a self-written site on a CMS happen?
What mistakes should be avoided?

Answer 1

What mistakes should be avoided?

Aimless body movements.
Why are you moving?
The best option for translating a self-written site to an engine is the Fat-Free Framework engine

Fast and clean template engine
Unit testing toolkit
Database-managed sessions
Markdown-to-HTML converter
Atom/RSS feed reader
Image processor
Geodata handler
On-the-fly Javascript/CSS compressor
OpenID (consumer)
Custom logger
Basket/Shopping cart
Pingback server/consumer
Unicode-aware string functions
SMTP over SSL/TLS
Tools for communicating with other servers
Data Validation

Answer 2

Traffic is good, but without the site itself, you can’t even remotely tell which CMS will suit it.

Answer 3

I'll reformulate your question:

Cooking on the stove, with four burners.
I want to change the taste of food.
Please tell me which seasonings to choose or at least which ones to look at?
How does cooking work with seasonings?
What mistakes should be avoided?

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CMS/Frameworks/... are tools for solving specific problems. The choice of tool is based on what tasks you are going to solve.
Traffic 50k per day - what is 50k? Requests, gigabit, registrations, payments, streams, publications, transactions.
To evaluate traffic from the technical side, there are 2 main metrics: RPS (Request Per Second) and *bit/s (number of bits per second)