Xeons are not magically faster than their i7/i9 counterparts (mine being not faster than a i7-7820HQ which is its contemporary flagship high performance mobile CPU). In fact they can be slower because the emphasis is on correctness and multi core, not usually single thread performance.
Xeons are also slower than a modern AMD chip which also can have more cores.
5x is a performance metric that doesn’t match up. Unless you have a desktop class 145w/165w cpu, in which case it’s not going to get 9hrs of battery unless you’re not actually touching the CPU. More like 30 minutes of heavy use on the largest battery legally allowed in laptops.
Edit: I just took a quick snoop on geek bench and found a modern xeon w in the largest dell precision laptop available:
Single core: 929 vs 1783 for M1
Multi core: 6718 vs 12693 for M1
https://browser.geekbench.com/v5/cpu/10517773
Synthetic scores aren’t everything, but I’m hard pressed seeing how you can get 5x performance out of a chip that scores almost exactly half. Even with hardware accelerations like AVX512 (which causes a cpu to get so hot it throttles below baseline even on servers with more than adequate cooling.)