create database '/var/tmp/test.fdb' page_size 8192 user 'SYSDBA' password 'm';
create table test(id integer not null primary key, val double precision);
set term ^ ;
execute block as declare variable i integer; begin delete from test; i = 0; while (i < 1000000) do begin i = i + 1; insert into test values(:i, rand()); end end^
commit ^
exit ^

time (echo 'update test set val = rand(); commit;' | isql-fb -u SYSDBA -p m localhost:/var/tmp/test.fdb)

0m15,801s
0m35,838s
0m37,781s
time cp --reflink=always test.fdb test-r0.fdb # 0m0,007s
 0m55,574s 
0m39,688s
0m39,192s
time rm -f test-r0.fdb # 0m0,006s
0m39,255s
0m38,928s
0m38,400s
time cp --reflink=always test.fdb test-r0.fdb # 0m0,024s
 1m0,041s 
0m40,366s
0m39,914s

0m10,044s
0m17,530s
0m17,517s
time cp --reflink=always test.fdb test-r0.fdb # 0m0,170s
0m17,510s
0m17,566s
0m17,563s
time rm -f test-r0.fdb # 0m0,007s
0m17,554s
0m17,610s
0m17,584s
time cp --reflink=always test.fdb test-r0.fdb # 0m0,170s
0m17,555s
0m17,562s
0m17,561s
time sync # 0m0,139s