FindChildByXpath method is very very slow all of sudden

I'm guessing that the reason for the slowness is the "not found" aspect.  There's atimeout for searching for objects and you may be hitting that time out.  If the code snippet you posted is not returning an object, than it's entirely the case that the XPath may have changed. You might need to rework that code.  I'm guessing that the problem is in Chrome or how Chrom is rendering the web page, not necessarily in TestComplete.