diff --git a/TODO.FACTOR.txt b/TODO.FACTOR.txt
index 2a9d1e3723..0f483351c9 100644
--- a/TODO.FACTOR.txt
+++ b/TODO.FACTOR.txt
@@ -1,5 +1,3 @@
-- timeouts broken on unix
-
 + ui:
 
 - fix listener prompt display after presentation commands invoked
diff --git a/library/collections/sequences-epilogue.factor b/library/collections/sequences-epilogue.factor
index 774b0d6edc..f2aa932e3d 100644
--- a/library/collections/sequences-epilogue.factor
+++ b/library/collections/sequences-epilogue.factor
@@ -164,13 +164,13 @@ M: object >list ( seq -- list ) dup length 0 rot (>list) ;
     #! Return a new sequence of the same type as s1.
     rot [ [ rot nappend ] keep swap nappend ] immutable ;
 
-M: f concat ;
-
-M: cons concat
-    unswons [ swap [ nappend ] each-with ] immutable ;
-
-M: object concat
-    >list concat ;
+: concat ( seq -- seq )
+    #! Append a sequence of sequences together. The new sequence
+    #! has the same type as the first sequence.
+    dup empty? [
+        [ 1024 <vector> swap [ dupd nappend ] each ] keep
+        first like
+    ] unless ;
 
 M: object peek ( sequence -- element )
     #! Get value at end of sequence.
diff --git a/library/compiler/optimizer.factor b/library/compiler/optimizer.factor
index 6a6d98d855..682300ae26 100644
--- a/library/compiler/optimizer.factor
+++ b/library/compiler/optimizer.factor
@@ -196,7 +196,7 @@ M: #values can-kill* ( literal node -- ? )
     ] ifte ;
 
 : branch-values ( branches -- )
-    [ last-node node-in-d >list ] map
+    [ last-node node-in-d ] map
     unify-lengths seq-transpose branch-returns set ;
 
 : can-kill-branches? ( literal node -- ? )
diff --git a/library/inference/partial-eval.factor b/library/inference/partial-eval.factor
index 606aa3948a..850c0a7212 100644
--- a/library/inference/partial-eval.factor
+++ b/library/inference/partial-eval.factor
@@ -5,11 +5,8 @@ USING: generic interpreter kernel lists math namespaces
 sequences words ;
 
 : literal-inputs? ( in stack -- )
-    tail-slice* dup >list [ safe-literal? ] all? [
-        length #drop node, t
-    ] [
-        drop f
-    ] ifte ;
+    tail-slice* dup [ safe-literal? ] all?
+    [ length #drop node, t ] [ drop f ] ifte ;
 
 : literal-inputs ( out stack -- )
     tail-slice* [ literal-value ] nmap ;
diff --git a/library/test/math/matrices.factor b/library/test/math/matrices.factor
index 48e30d0912..cf9a1978a0 100644
--- a/library/test/math/matrices.factor
+++ b/library/test/math/matrices.factor
@@ -1,5 +1,6 @@
 IN: temporary
-USING: kernel lists math matrices namespaces sequences test ;
+USING: kernel lists math matrices namespaces sequences test
+vectors ;
 
 [ [ [ 1 4 ] [ 2 5 ] [ 3 6 ] ] ]
 [ M[ [ 1 4 ] [ 2 5 ] [ 3 6 ] ]M row-list ] unit-test
@@ -131,10 +132,10 @@ unit-test
 ] unit-test
 
 [
-    [ [ 7 ] [ 4 8 ] [ 1 5 9 ] [ 2 6 ] [ 3 ] ]
+    [ { 7 } { 4 8 } { 1 5 9 } { 2 6 } { 3 } ]
 ] [
     M[ [ 1 2 3 ] [ 4 5 6 ] [ 7 8 9 ] ]M
-    5 [ 2 - swap <diagonal> ] project-with [ >list ] map
+    5 [ 2 - swap <diagonal> ] project-with [ >vector ] map
 ] unit-test
 
 [ { t t t } ]
diff --git a/library/test/sequences.factor b/library/test/sequences.factor
index 2d53dcd7eb..abbe3cd98b 100644
--- a/library/test/sequences.factor
+++ b/library/test/sequences.factor
@@ -1,11 +1,11 @@
 IN: temporary
 USING: kernel lists math sequences strings test vectors ;
 
-[ [ 1 2 3 4 ] ] [ 1 5 <range> >list ] unit-test
+[ { 1 2 3 4 } ] [ 1 5 <range> >vector ] unit-test
 [ 3 ] [ 1 4 <range> length ] unit-test
-[ [ 4 3 2 1 ] ] [ 4 0 <range> >list ] unit-test
+[ { 4 3 2 1 } ] [ 4 0 <range> >vector ] unit-test
 [ 2 ] [ 1 3 { 1 2 3 4 } <slice> length ] unit-test
-[ [ 2 3 ] ] [ 1 3 { 1 2 3 4 } <slice> >list ] unit-test
+[ { 2 3 } ] [ 1 3 { 1 2 3 4 } <slice> >vector ] unit-test
 [ { 4 5 } ] [ 2 { 1 2 3 4 5 } tail-slice* >vector ] unit-test
 [ { 1 2 } { 3 4 } ] [ 2 { 1 2 3 4 } cut ] unit-test
 [ { 1 2 } { 4 5 } ] [ 2 { 1 2 3 4 5 } cut* ] unit-test
diff --git a/library/test/strings.factor b/library/test/strings.factor
index 24f600ce4a..f0c95570d2 100644
--- a/library/test/strings.factor
+++ b/library/test/strings.factor
@@ -1,4 +1,5 @@
 IN: temporary
+USING: vectors ;
 USE: errors
 USE: kernel
 USE: math
@@ -96,4 +97,4 @@ unit-test
 [ 1 "" nth ] unit-test-fails
 [ -6 "hello" nth ] unit-test-fails
 
-[ t ] [ "hello world" dup >list >string = ] unit-test 
+[ t ] [ "hello world" dup >vector >string = ] unit-test 
diff --git a/library/ui/presentations.factor b/library/ui/presentations.factor
index 3710bc4607..9310b05d4b 100644
--- a/library/ui/presentations.factor
+++ b/library/ui/presentations.factor
@@ -11,8 +11,8 @@ global [ 100 <vector> commands set ] bind
 : define-command ( class name quot -- )
     3list commands get push ;
 
-: applicable ( object -- list )
-    commands get >list [ car call ] subset-with ;
+: applicable ( object -- seq )
+    commands get [ car call ] subset-with ;
 
 : command-quot ( presented quot -- quot )
     [ swap literal, % ] make-list