You will need to dramatically broaden your skills base, for the jump from a manual tester to a performance tester is quite large. There are many posts on the Internet which speak to "foundation skills" for a performance tester. Find them (using one of the core skills: research) and take them to heart. For if you have the core skills in place you can be at 95% of capability within about six weeks. If you lack sold core foundation skills you will struggle, have low efficiency and demonstrate low output to your clients for the entire time you are in the profession.
Once you have mastered your core skills, then you can look at tools and a program where you have a mentor for your first six months or so. The tool is really only 10-15% of the skills required for a successful performance tester. Mind you it is a critical 10-15% and unless you have mastered some of the foundation skills you will never be able to master the tool. There are also process and project management skills which come into play which you will acquire during the internship.
Can you get there? Yes. Be prepared to spend a year or longer coming from a manual functional testing background. If you think just learning a tool will get the job done then you will be joining a growing problem in our industry which is delivery of low value services which are damaging the value base and which has resulted in an odd economic condition where the average value of what is being delivered is so low that it has overwhelmed the natural tendency of wages to rise in a low resource condition.
