Hi there,
Thanks for sharing your requirement of wordpress developer for fixing bug and speeding up your site. I have more than 9 years of experience developing wordpress website.
As you mentioned "I DO NOT want a user who will just do a few tweaks and then say "oh well it is working on my end just check with your hosting provider" >> i wont tell you the same, you will see the result by yourself only.
In my 9 years in the Web and Mobile development industry, I have worked in over 60 complex projects as a team that were responsible for the design(UI/UX) and development. I am an expert in PHP, Wordpress,Prestashop, HTML5, CSS3, Bootstrap, responsive designs and many more.
I believe my skills and experiences fit your requirements and will be grateful if you give me a chance for an interview with you at a time that's convenient to you.
Please feel free to contact me through Message Board, I will be happy to get back you as soon as possible. I assure you of confirmed delivery within the timeline.
Best regards,
Parth