Nikita,
Salesforce puts custom pages into their own namespace. Try changing the URL of your iframe to->
src=“c__PerfiosAccountOverview?id={{{Id}}}”
Note that you can also add this parameter to the URL to hide the header/sidebar-> &isdtp=vw
src=“c__PerfiosAccountOverview?id={{{Id}}}isdtp=vw”
Thanks,
Bill