In general the TP-Links authenticate a tad faster than some other routers, there are many factors at play from start-up to syncing & auth. Different devices uses different measures - some sync faster but auth. slower and others differently, some use the 3-pass step, others the 4-5pass and some even a 7pass from power down to a full Auth. Factors like the Memory, Boot-loaders, Encryption methods, MIPS etc. comes into play - so it's really device depending.
The best way probably is to power-down - disconnect all client devices, incl wireless from the router and perform a start-up & sync to get some idea.
Most higher-end routers takes a bit longer due to system checks as mentioned before initialising syncing & authenticating. Your DSL-Line-state, Exchange connected to, ISP also determine the time frame.
So, as long a the bloody thing connects you're fine
