library(terra)
#> terra 1.5.34
r <- rast("/vsicurl/https://dapds00.nci.org.au/thredds/fileServer/gb6/BRAN/BRAN2020/daily/ocean_u_2010_01.nc", lyrs = 1:10)
crs(r) <- "EPSG:4326"
e <- ext(c(xmin = 104, xmax = 138, ymin = 13, ymax = 32))
## set up a lower resolution
target_rast <- crop(rast(r), e)
res(target_rast) <- res(target_rast) * 4
system.time(project(r, target_rast, gdal = TRUE))
#> user system elapsed
#> 0.653 0.144 4.678
## or just crop a template of the data
system.time(project(r, crop(rast(r), e), gdal = TRUE))
#> user system elapsed
#> 0.480 0.050 0.551
Created on 2022-07-08 by the reprex package (v2.0.1)