I've noticed some rendering differences between 8u25 and 8u40. I'm not certain if they are bugs or just fixes and I was expecting the buggy behaviour.
For example, after coloring in the background on the SVG curved edge at the button corner of my widget I can better understand the artifacting I see only with 8u40.

Here's the test app:

package renderissues;

import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.Slider;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Region;
import javafx.scene.layout.StackPane;
import javafx.scene.shape.Circle;
import javafx.scene.shape.LineTo;
import javafx.scene.shape.MoveTo;
import javafx.scene.shape.Path;
import javafx.scene.shape.PathElement;
import javafx.scene.transform.Transform;
import javafx.stage.Stage;

public class RenderIssues extends Application {

    @Override
    public void start(Stage primaryStage) {
        Region cornerBackground = new Region(); // shape defined in CSS
        cornerBackground.setStyle("-fx-background-color: YELLOW;" +
            "-fx-position-shape: false;" +
            "-fx-scale-shape: false;" +
            "-fx-shape: \"m37,26.65l0,-15.20 c0,-5.21335 -4.48,-9.44446 -10,-9.44446 l-27,0 l0,26.55 c0,7 1.5,7.6 12,7.5 l24,0 l10,0 c-5.49,0 -9.94,-4.17447 -9,-9.35001 z\";" +
            "-fx-translate-x: 1;" +
            "-fx-translate-y: -4;" +
            "-fx-padding: 0;");

        Region cornerBorder = new Region(); // shape defined in CSS
        cornerBorder.setStyle("-fx-background-color: PINK;" +
            "-fx-border-color: BLACK;\n" +
            "-fx-position-shape: false; " +
            "-fx-scale-shape: false; " +
            "-fx-shape: \"M0,0h26c6.07,0,11,4.93,11,11 v16C37.05,32,41,35,46,35\"; " +
            "-fx-translate-x: 1; " +
            "-fx-translate-y: -2.5; " +
            "-fx-padding: 0;");

        Circle cornerButton = new Circle();
cornerButton.setRadius(16);

        StackPane cornerSP = new StackPane();
        cornerSP.getChildren().addAll(cornerBackground, cornerBorder, cornerButton);

        BorderPane box = new BorderPane();
        box.setStyle("-fx-border-color: rgb(0,0,0), linear-gradient(rgb(140,140,140) 0%, rgb(80,80,80) 5%, rgb(140,140,140) 10%, rgb(80,80,80) 90%, rgb(140,140,140) 100%);" +
            "-fx-border-width: 5,2;" +
            "-fx-border-radius: 8,9;" +
            "-fx-border-insets: -2 10 4 10, -1 11 5 11;" +
            "-fx-background-color: GREEN;" +
            "-fx-background-radius: 7;" +
            "-fx-background-insets: 2 11 6 11;" +
            "-fx-padding: 0 -2 0 -1;");
        HBox titleBar = new HBox();
        titleBar.setStyle("-fx-background-radius: 7 7 0 0;" +
            "-fx-background-insets: 0 0 1 0;" +
            "-fx-background-color: linear-gradient(to bottom, black, rgba(255,255,255,0));" +
            "-fx-border-color: componentBorderColor;" +
            "-fx-border-width: 0 0 1 0;");
        box.setTop(titleBar);
        Label title = new Label("This renders differently in 8u20 and 8u40");
        title.setStyle("-fx-text-fill: WHITE;");
        titleBar.getChildren().add(title);

        Region arrowhead = new Region();
        arrowhead.setStyle("-fx-position-shape: false;" +
            "-fx-scale-shape: false;" +
            "-fx-shape: \"M0,0L8,3L8-3z\";" +
            "-fx-border-color: LIGHTBLUE;" +
            "-fx-border-width: 2;" +
            "-fx-border-insets: -1;" +
            "-fx-background-color: LIGHTBLUE;");
        Path line = new Path();
        line.setStyle("-fx-stroke: LIGHTBLUE;" +
            "-fx-stroke-width: 2.25;" +
            "-fx-stroke-line-cap: round;");
        double eX = 50;
        double eY = 0;
        PathElement start = new MoveTo(0, 0);
        PathElement end = new LineTo(eX, eY);
        line.getElements().addAll(start,end);
        arrowhead.getTransforms().add(Transform.rotate(180, 0, 0));
        arrowhead.setLayoutX(eX);
        arrowhead.setLayoutY(eY);
        Group pathGroup = new Group(line, arrowhead);
        box.setCenter(pathGroup);
        HBox bottom = new HBox(cornerSP);
        box.setBottom(bottom);
        Group content = new Group(box);
        BorderPane bp = new BorderPane(content);
        Slider zoomer = new Slider(1, 10, 3);
        box.scaleXProperty().bind(zoomer.valueProperty());
        box.scaleYProperty().bind(zoomer.valueProperty());
        bp.setTop(zoomer);
        Scene scene = new Scene(bp, 700, 250);
        primaryStage.setTitle("Render Issues");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    public static void main(String[] args) { launch(args); }
}