speed issue DBR 13+ for R

[romangehrn]

I got a notebook running on DBR 12.2 with the following R code:

install.packages("microbenchmark") 
install.packages("furrr") 

library(microbenchmark) 
library(tidyverse) 
# example tibble 
df_test <- tibble(id = 1:100000, street_raw = rep("Bahnhofstrasse 12", 100000)) 

# function 
test_fc <- function(str = "") { 
value = str_to_lower(str) 
value = str_replace_all(value, pattern="n", replacement="N") 
value = str_replace_all(value, pattern="h", replacement="H") 
return(value) } 

# single core with purrr package 
microbenchmark(df_test %>% mutate(street_all = map_chr(street_raw, test_fc)), times = 10) 

# DBR 12.2 / median 9.300949 seconds 
# DBR 13.2 / median 16.04199 seconds 

# multi core with furrr package 
library(furrr) 
plan(multisession) 

microbenchmark(df_test %>% mutate(street_all = future_map_chr(street_raw, test_fc)), times = 10) 

# DBR 12.2 / median 1.861389 seconds 
# DBR 13.2 / median 2.781327 seconds 

with a cluster (Standard_F8s, 16GB RAM, 8 Core) DBR 12.2 i got the result in:
single core 9.30s / multi core 1.86s

with the same cluster and DBR 13.2 i got the result in:
single core 16.04s / multi core 2.78s

Can anyone give me some advise to speed up also with DBR 13+ or is it in general slower?