Performance appending to an array column

I'm considering a table structure where I'd be continuously appending
to long arrays of floats (10 million elements or more). Keeping the
data in arrays gives me much faster SELECT performance vs keeping it
in millions of rows.

But since these arrays keep growing, I'm wondering about the UPDATE
performance. I was reading this commit message about improving
performance of *overwriting* individual array elements, and I was
wondering if there is anything similar for growing an array column?:

https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=1dc5ebc9077ab742

Is there a faster way to append to an array than just this?:

UPDATE measurements
SET vals = vals || ARRAY[5.0, 4.2, 9.9]::float[]
;

Thanks!
Paul