diff --git a/MetaBrush.cabal b/MetaBrush.cabal
index daf9a81..5893218 100644
--- a/MetaBrush.cabal
+++ b/MetaBrush.cabal
@@ -159,15 +159,17 @@ common gtk
       , gi-gtk
            >= 4.0.3      && < 4.1
       , haskell-gi
-           >= 0.26       && < 0.27
+           >= 0.26.10    && < 0.27
       , haskell-gi-base
-           >= 0.26       && < 0.27
+           >= 0.26.10    && < 0.27
 
     -- Workaround for https://github.com/haskell/cabal/issues/4237
     -- See https://github.com/commercialhaskell/stack/issues/2197
     if flag(gtk-410)
       pkgconfig-depends: gtk4 >= 4.10
       cpp-options: -DMIN_VERSION_GTK_4_10
+    else
+      pkgconfig-depends: gtk4 < 4.10
 
 library metabrushes
 
diff --git a/brush-strokes/brush-strokes.cabal b/brush-strokes/brush-strokes.cabal
index f695bea..36703eb 100644
--- a/brush-strokes/brush-strokes.cabal
+++ b/brush-strokes/brush-strokes.cabal
@@ -199,11 +199,18 @@ library
       cbits/lp_2d.cpp
     cxx-options:
       -std=c++20
-      -mavx2 -mfma
-      -frounding-math -fno-math-errno -fno-signed-zeros
-      -fno-trapping-math -fno-signaling-nans
-      -Wno-unused-result -Wsign-compare -Wno-switch
-      -march=native -mtune=native
+      -mavx2
+      -mfma
+      -frounding-math
+      -ffp-contract=off
+      -fno-math-errno
+      -fno-signed-zeros
+      -fno-trapping-math
+      -Wno-unused-result
+      -Wno-sign-compare
+      -Wno-switch
+      -march=native
+      -mtune=native
       -O3 -DNDEBUG
     build-depends:
       system-cxx-std-lib
diff --git a/brush-strokes/src/lib/Math/Interval/Internal.hs b/brush-strokes/src/lib/Math/Interval/Internal.hs
index 026e090..3a81335 100644
--- a/brush-strokes/src/lib/Math/Interval/Internal.hs
+++ b/brush-strokes/src/lib/Math/Interval/Internal.hs
@@ -131,6 +131,12 @@ instance Transcendental ( 𝕀 Double ) where
   sin = withHW Prelude.sin
   atan = withHW Prelude.atan
 
+{-
+TODO: consider using https://github.com/JishinMaster/simd_utils/blob/160c50f07e08d2077ae4368f0aed2f10f7173c67/simd_utils_sse_double.h#L530
+for sin/cos? Or Intel SVML? Or metalibm?
+
+-}
+
 {-# INLINE withHW #-}
 -- | Internal function: use @rounded-hw@ to define a function on intervals.
 withHW :: (Interval.Interval a -> Interval.Interval b) -> 𝕀 a -> 𝕀 b
diff --git a/brush-strokes/src/lib/Math/Root/Isolation.hs b/brush-strokes/src/lib/Math/Root/Isolation.hs
index 70f93a6..16d6b2c 100644
--- a/brush-strokes/src/lib/Math/Root/Isolation.hs
+++ b/brush-strokes/src/lib/Math/Root/Isolation.hs
@@ -65,6 +65,10 @@ import qualified Data.List.NonEmpty as NE
 import GHC.TypeNats
   ( Nat )
 
+-- parallel
+--import Control.Parallel.Strategies
+--  ( Strategy, using, parTraversable, rpar )
+
 -- transformers
 import Control.Monad.Trans.Writer.CPS
   ( Writer, runWriter, tell )
@@ -248,10 +252,18 @@ isolateRootsIn ( RootIsolationOptions { rootIsolationAlgorithms } )
           -> [ Box n ]
           -> Writer ( DoneBoxes n ) [ RootIsolationTree ( Box n ) ]
     recur step r cands = do
-      rest <- traverse ( \ c -> do { trees <- r c; return [ (c, tree) | tree <- trees ] } ) cands
-      return [ RootIsolationStep step $ concat rest ]
+      let rest :: [ ( [ ( Box n, RootIsolationTree ( Box n ) ) ], DoneBoxes n ) ]
+          rest =
+            map ( \ c -> runWriter $ do { trees <- r c; return [ (c, tree) | tree <- trees ] } ) cands
+          ( rest2, dones ) = unzip rest --( rest `using` myParTraversable rpar )
+      tell ( mconcat dones )
+      return [ RootIsolationStep step $ concat rest2 ]
 {-# INLINEABLE isolateRootsIn #-}
 
+--myParTraversable :: Strategy a -> Strategy [a]
+--myParTraversable _ [] = return []
+--myParTraversable strat (a:as) = (a:) <$> parTraversable strat as
+
 -- | Execute a root isolation strategy, replacing the input box with
 -- (hopefully smaller) output boxes.
 doStrategy
diff --git a/cabal.project b/cabal.project
index 5042c09..38c14c5 100644
--- a/cabal.project
+++ b/cabal.project
@@ -41,12 +41,6 @@ allow-newer:
   waargonaut:vector,
   waargonaut:witherable,
 
--- Fix "ERROR: couldn't find API description for GLib.time_t"
-source-repository-package
-  type: git
-  location: https://github.com/sheaf/haskell-gi
-  tag: ec11dd69ab6a3a9f7f7e967f5f7ffa7d9206cd2a
-
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 -- GHC 9.10 --
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