diff --git a/NEWS.md b/NEWS.md
index fa5fa3e79b..0b762ca3db 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -162,6 +162,8 @@
 
 23. Added a `data.table` method for `utils::edit` to ensure a `data.table` is returned, for convenience, [#593](https://github.com/Rdatatable/data.table/issues/593).
 
+24. More efficient optimization of many columns in `j` (e.g. from `.SD`), [#1470](https://github.com/Rdatatable/data.table/issues/1470). Thanks @Jorges1000 for the report.
+
 #### BUG FIXES
 
 1. `first`, `last`, `head` and `tail` by group no longer error in some cases, [#2030](https://github.com/Rdatatable/data.table/issues/2030) [#3462](https://github.com/Rdatatable/data.table/issues/3462). Thanks to @franknarf1 for reporting.
diff --git a/R/data.table.R b/R/data.table.R
index 6cc4b9cde9..43541e9afb 100644
--- a/R/data.table.R
+++ b/R/data.table.R
@@ -1611,11 +1611,11 @@ replace_order = function(isub, verbose, env) {
     }
     if (verbose) {
       if (!identical(oldjsub, jsub))
-        cat("lapply optimization changed j from '",deparse(oldjsub),"' to '",deparse(jsub,width.cutoff=200L),"'\n",sep="")
+        cat("lapply optimization changed j from '",deparse(oldjsub),"' to '",deparse(jsub,width.cutoff=200L, nlines=1L),"'\n",sep="")
       else
-        cat("lapply optimization is on, j unchanged as '",deparse(jsub,width.cutoff=200L),"'\n",sep="")
+        cat("lapply optimization is on, j unchanged as '",deparse(jsub,width.cutoff=200L, nlines=1L),"'\n",sep="")
     }
-    dotN = function(x) is.name(x) && x == ".N" # For #5760
+    dotN = function(x) is.name(x) && x==".N" # For #5760. TODO: Rprof() showed dotN() may be the culprit if iterated (#1470)?; avoid the == which converts each x to character?
     # FR #971, GForce kicks in on all subsets, no joins yet. Although joins could work with
     # nomatch=0L even now.. but not switching it on yet, will deal it separately.
     if (getOption("datatable.optimize")>=2 && !is.data.table(i) && !byjoin && length(f__) && !length(lhs)) {
@@ -1643,7 +1643,9 @@ replace_order = function(isub, verbose, env) {
         }
         if (jsub[[1L]]=="list") {
           GForce = TRUE
-          for (ii in seq_along(jsub)[-1L]) if (!.ok(jsub[[ii]])) GForce = FALSE
+          for (ii in seq.int(from=2L, length.out=length(jsub)-1L)) {
+            if (!.ok(jsub[[ii]])) {GForce = FALSE; break}
+          }
         } else GForce = .ok(jsub)
         if (GForce) {
           if (jsub[[1L]]=="list")
@@ -1665,12 +1667,15 @@ replace_order = function(isub, verbose, env) {
       nomeanopt=FALSE  # to be set by .optmean() using <<- inside it
       oldjsub = jsub
       if (jsub[[1L]]=="list") {
-        for (ii in seq_along(jsub)[-1L]) {
-          this_jsub = jsub[[ii]]
-          if (dotN(this_jsub)) next; # For #5760
-          # Addressing #1369, #2949 and #1974. Added is.symbol() check to handle cases where expanded function definition is used instead of function names. #1369 results in (function(x) sum(x)) as jsub[[.]] from dcast.data.table.
-          if (is.call(this_jsub) && is.symbol(this_jsub[[1L]]) && this_jsub[[1L]]=="mean")
-            jsub[[ii]] = .optmean(this_jsub)
+        # Addressing #1369, #2949 and #1974. This used to be 30s (vs 0.5s) with 30K elements items in j, #1470. Could have been dotN() and/or the for-looped if()
+        todo = sapply(jsub, function(x) {
+          is.call(x) && is.symbol(x[[1L]]) && x[[1L]]=="mean"
+          # jsub[[1]]=="list" so the first item will always be FALSE
+          # is.symbol() for when expanded function definition is used instead of function names; #1369 results in (function(x) sum(x)) as jsub[[.]] from dcast.data.table
+        })
+        if (any(todo)) {
+          w = which(todo)
+          jsub[w] = lapply(jsub[w], .optmean)
         }
       } else if (jsub[[1L]]=="mean") {
         jsub = .optmean(jsub)